JP3718955B2 - Filled polytetrafluoroethylene granular powder and process for producing the same - Google Patents

Description

（式中、ｍは０または１〜４の整数である）で示される有機基または式（III）：
【００３１】
【化２】

（式中、ｎは１〜４の整数である）で示される有機基を表わす］で示されるパーフルオロビニルエーテルなどがあげられる。
【００３２】
前記パーフルオロアルキル基の炭素数は１〜１０、好ましくは１〜５であり、炭素数をこの範囲内の数とすることにより溶融成形不可という性質を保持したまま、耐クリープ性に優れているという効果がえられる。
【００３３】
前記パーフルオロアルキル基としては、たとえばパーフルオロメチル、パーフルオロエチル、パーフルオロプロピル、パーフルオロブチル、パーフルオロペンチル、パーフルオロヘキシルなどがあげられるが、耐クリープ性およびモノマーコストの点からパーフルオロプロピルが好ましい。
【００３４】
前記ＴＦＥと共重合が可能な単量体の重合割合を１．０〜０．００１モル％の範囲内の割合とすることにより耐クリープ性に優れているという効果がえられる。
【００３５】
前記ＰＴＦＥ粉末またはＰＴＦＥ含水粉末の粒子の平均粒径を前記範囲内の粒径とすることにより、造粒してえられる粒状粉末の取扱い性すなわち粉末流動性および見かけ密度に優れ、しかもえられる成形品物性に優れているという効果がえられる。
【００３６】
本発明において用いるフィラーのうち、親水性フィラーのばあい、フィラーが親水性のため水相に移行しやすく、ＰＴＦＥ粉末と均一に混合しにくい、すなわち使用したフィラーの全部がＰＴＦＥ粉末と混合した粒状粉末がえられず、その一部は処理水中に残留するという難点がある。この現象はフィラーの分離とよばれる。
【００３７】
この問題に対処し、親水性フィラーをあらかじめ疎水化表面処理して、その表面活性を低下させてＰＴＦＥ粉末の粒子の表面活性に近づけておいてから水中で撹拌を行なうなどの方法が採用される。
【００３８】
このような表面処理をするための化合物として知られているものには、（ａ）アミノ官能基を有するシラン、フェニル基を有するシランおよび（または）可溶なシリコーン（特開昭５１−５４８号公報、特開昭５１−５４９号公報、特開平４−２１８５３４号公報）、（ｂ）炭素数１２〜２０の炭化水素のモノカルボン酸（特公昭４８−３７５７６号公報）、（ｃ）脂肪族カルボン酸のクロム錯化合物（特公昭４８−３７５７６号公報）、（ｄ）シリコーン（特開昭５３−１３９６６０号公報）などがあり、また（ｅ）親水性フィラーをＰＴＦＥそのもので被覆する方法（特開昭５１−１２１４１７号公報）も知られている。
【００３９】
前記した親水性フィラーの表面処理をするためのより具体的な化合物としては、たとえばγ−アミノプロピルトリエトキシシラン（Ｈ₂Ｎ（ＣＨ₂）₃Ｓｉ（ＯＣ₂Ｈ₅）₃）、ｍ−またはｐ−アミノフェニルトリエトキシシラン（Ｈ₂Ｎ−Ｃ₆Ｈ₄−Ｓｉ（ＯＣ₂Ｈ₅）₃）、γ−ウレイドプロピルトリエトキシシラン（Ｈ₂ＮＣＯＮＨ（ＣＨ₂）₃Ｓｉ（ＯＣ₂Ｈ₅）₃、Ｎ−（β−アミノエチル）−γ−アミノプロピルトリメトキシシラン（Ｈ₂Ｎ（ＣＨ₂）₂ＮＨ（ＣＨ₂）₃Ｓｉ（ＯＣＨ₃）₃）、Ｎ−（β−アミノエチル）−γ−アミノ−プロピルメチルジメトキシシラン（Ｈ₂Ｎ（ＣＨ₂）₂ＮＨ（ＣＨ₂）₃ＳｉＣＨ₃（ＯＣＨ₃）₂）などのアミノシランカップリング剤などがあげられる。また、これらの化合物以外に、たとえばフェニルトリメトキシシラン、フェニルトリエトキシシラン、ｐ−クロロフェニルトリメトキシシラン、ｐ−ブロモメチルフェニルトリメトキシシラン、ジフェニルジメトキシシラン、ジフェニルジエトキシシラン、ジフェニルシランジオールなどの有機シラン化合物があげられる。
【００４０】
なお、フィラーが撥水性を有しているばあいは、そのままで用いることができる。
【００４１】
前記フィラーとしては、たとえばガラス繊維、グラファイト粉末、青銅粉末、金粉末、銀粉末、銅粉末、ステンレス鋼粉末、ステンレス鋼繊維、ニッケル粉末、ニッケル繊維などの金属繊維または金属粉末、二硫化モリブデン粉末、フッ化雲母粉末、コークス粉末、カーボン繊維、チッ化ホウ素粉末、カーボンブラックなどの無機系繊維または無機系粉末、ポリオキシベンゾイルポリエステルなどの芳香族系耐熱樹脂粉末、ポリイミド粉末、テトラフルオロエチレン−パーフルオロ（アルキルビニルエーテル）共重合体（ＰＦＡ）粉末、ポリフェニレンサルファイド粉末などの有機系粉末などの１種または２種以上のフィラーがあげられるが、これらに限定されるものではない。
【００４２】
２種以上のフィラーを用いるばあい、たとえばガラス繊維とグラファイト粉末、ガラス繊維と二硫化モリブデン粉末、青銅粉末と二硫化モリブデン粉末、青銅粉末とカーボン繊維、グラファイト粉末とコークス粉末、グラファイト粉末と芳香族系耐熱樹脂粉末、カーボン繊維と芳香族系耐熱樹脂粉末などの組合せが好ましく、混合法は湿式法でも乾式法でもよい。
【００４３】
本発明のフィラー入りＰＴＦＥ粒状粉末はＰＴＦＥ部分の白色度が高く、したがって、フィラーとして白色または透明なもの、たとえばガラス繊維、チッ化ホウ素粉末、酸化チタン粉末などを用いるばあい、従来にない高い白色度（Ｚ値）の成形品がえられる。
【００４４】
前記フィラーは、粉末のばあい平均粒径が１０〜１０００μｍであることが、繊維のばあい平均繊維長が１０〜１０００μｍであることが好ましい。
【００４５】
前記ＰＴＦＥ粉末とフィラーとの混合割合としては、ＰＴＦＥ粉末１００部（重量部、以下同様）に対して、前記フィラー２．５〜１００部であることが好ましく、５〜８０部であることがさらに好ましい。
【００４６】
本発明において用いる有機液体は、水と液−液界面を形成し水中に液滴として存在しうる有機液体であればよく、水中で液滴を形成し水と液−液界面を形成しうるものであれば水に多少溶解するものであってもよい。具体例としては、たとえば１−ブタノール、１−ペンタノールなどのアルコール類；ジエチルエーテル、ジプロピルエーテルなどのエーテル類；メチルエチルケトン、２−ペンタノンなどのケトン類；ペンタン、ドデカンなどの脂肪族炭化水素；ベンゼン、トルエン、キシレンなどの芳香族炭化水素；塩化メチレン、テトラクロロエチレン、トリクロロエチレン、クロロホルム、クロロベンゼン、トリクロロトリフルオロエタン、モノフルオロトリクロロメタン、ジフルオロテトラクロロエタン、１，１，１−トリクロロエタン、１，１−ジクロロ−２，２，３，３，３−ペンタフルオロプロパン、１，３−ジクロロ−１，１，２，２，３−ペンタフルオロプロパン、１，１−ジクロロ−２，２，２−トリフルオロエタン、１，１−ジクロロ−１−フルオロエタンなどのハロゲン化炭化水素などを用いることができる。これらのうちハロゲン化炭化水素が好ましく、特に１，１，１−トリクロロエタン、１，１−ジクロロ−２，２，３，３，３−ペンタフルオロプロパン、１，３−ジクロロ−１，１，２，２，３−ペンタフルオロプロパン、１，１−ジクロロ−２，２，２−トリフルオロエタン、１，１−ジクロロ−１−フルオロエタンなどの塩化炭化水素やフッ化塩化炭化水素が好ましい。これらは不燃性であり、かつフロン規制の要求などを満足するからである。これらの有機液体は単独で用いてもよく、２種以上を組み合わせて用いてもよい。
【００４７】
前記水と液−液界面を形成する有機液体の添加量としては、ＰＴＦＥ粉末とフィラーとの合計量に対して３０〜８０％（重量％、以下同様）であり、４０〜６０％であることが好ましい。
【００４８】
本発明においては前記のように、水と液−液界面を形成する有機液体の液滴中においてフィラーを含むＰＴＦＥ粉末の造粒が進行すると思われるが、特定のノニオン性界面活性剤のはたらきにより、この液滴がより小さく、より球形に近い形状になるために、平均粒径が小さく、また球形に近い粒子がえられ、また粒状粉末の見かけ密度が大きくなるものと思われる。
【００４９】
特定のノニオン性界面活性剤は、炭素数３〜４のポリ（オキシアルキレン）単位からなる疎水性セグメントとポリ（オキシエチレン）単位からなる親水性セグメントとを有するセグメント化ポリアルキレングリコール類である。
【００５０】
疎水性セグメントと親水性セグメントを有するセグメント化ポリアルキレングリコール類としては、たとえば式（IV）：
【００５１】
【化３】

（式中、Ａは
【００５２】
【化４】

ｐは５〜２００の整数、ｑは２〜４００の整数）で示されるものが好ましい。これらのうち、ＰＴＦＥ樹脂に吸着されやすいという点からｐは１５〜４０、ｑは７〜１００が好ましい。市販品としては、たとえばプロノン＃２０８、プロノン＃１０４（いずれも日本油脂（株）製のノニオン性界面活性剤）などが利用できる。
【００５３】
前記特定のノニオン性界面活性剤の添加量としては、ＰＴＦＥ粉末とフィラーとの合計量に対して０．０１〜５％であり、０．１〜０．３％であることが好ましい。
【００５４】
この範囲内で界面活性剤を用いることにより、ほぼ球形で小粒径でかつ粒度分布がシャープであり粉末流動性に優れ、帯電量が小さく、かつ見かけ密度が大きい粒状粉末がえられるという効果がえられる。
【００５５】
なお、通常のノニオン性界面活性剤を用いると、ガラス繊維などのガラス、酸化チタン、チタン酸塩および／またはチッ化ホウ素などの白色のフィラーを用いるとき、用いる界面活性剤の種類によっては焼成後にえられる成形体が着色してしまうことがある。しかし、前記の特定のノニオン性界面活性剤を用いれば、白色のフィラーを用いるばあいにも着色しない白色度（Ｚ値）の高い成形体をうることができる。
【００５６】
前記製法（３）において、ＰＴＦＥ含水粉末の湿式粉砕は、湿式でかつ衝撃力によって粉砕する形式の粉砕機によって行なわれる。この種の粉砕機には各種のものが知られているが、前記湿式粉砕においては、粉砕と同時に所望の粒径まで粉砕された微粉末のみを連続的に取り出すことができることが望ましく、そのために衝撃力をハンマーによって加えるタイプの粉砕機から選択するばあいは、ハンマーの周速ができる限り大きいものが望ましい。
【００５７】
このような条件を満足する粉砕機のひとつは、たとえば奈良機械製作所（株）製の「自由粉砕機（ＪＩＹＵ ＭＩＬＬ）」があげられる。この粉砕機は、粉砕室が偏平のシリンダー形状を呈しており、その対向する２つの側壁に断面が長方形ないしは長楕円形の棒状突起が多数植え込まれ、粉砕室の中央に回転する円盤状のローターが前記２つの側壁面と平行に設置され、そのローターの表裏両面に側壁と同様の棒状突起が、ローターが回転したとき前記側壁の棒状突起と衝突しないように多数植え込まれている構造を有する。
【００５８】
前記ＰＴＦＥ含水粉末はこの粉砕機の中心部に供給されローターの回転の遠心力によって外周方向に吹き飛ばされつつ側壁とローターの棒状突起に衝突し、その衝撃力により粉砕される。粉砕室のローター回転方向外周には環状の多孔板が設けられ、多孔板の孔径より小さく粉砕された粒子のみがこの孔を通過して多孔板の外側に取り出される。この多孔板は、金属などの網でもよいし、金属などの薄板に多数の孔を穿ったものなど種々のものが採用できる。その孔径によってえられる粒子の粒子径は変化し、孔径が小さいほどえられる粒子の粒子径は小さくなるが、粒子が水で湿潤しているので、実際に取り出される粒子の粒径は、多孔板に開けられた各孔の孔径よりかなり小さくなる。
【００５９】
前記自由粉砕機が、粉末が湿潤状態であっても微粉砕できる理由のひとつは、たとえばロータの周速１００ｍ／ｓ程度の高速のローター回転速度がえられることにあると考えられる。
【００６０】
なお、ハンマータイプの粉砕機であって、前記自由粉砕機と同程度以上の周速のえられるものとして、たとえば細川ミクロン（株）製の「コロプレックス」や「コントラプレックス」、日本ニューマチック（株）製の「ファインミル」などがある。これらはいずれも乾式条件下の粉砕に適したものであって、水の共存下に使用すると周速が低下したり、分級機構として風力分級法を用いているため、粉砕物が濡れているばあい風力分級は機能せず、目的の粒径より大きい粒子が分級、排出されるという現象を起こしてしまう。また基本的に湿式粉砕による粉砕機としてコロイドミルや擂解機などの剪断ミルがあるが、これらの粉砕機では極端な剪断力によりＰＴＦＥ粉末が変質を受けるため使用できない。
【００６１】
本発明においては、造粒に際し、撹拌と粉末の解砕を併用する点にも特徴がある。
【００６２】
解砕は、一次粒子の二次的集合体としてすでに生成している適当な大きさの造粒物を部分的に解砕して二次粒子径を低下させる手段で、たとえばディスパー翼にて高速撹拌するという方法で行なうことができる。
【００６３】
撹拌と解砕は同時に並行して行なってもよいし、撹拌と解砕を別々に行なってもよい。
【００６４】
撹拌と解砕を併用することにより、見かけ密度が高く、細粒化された造粒物がえられるという優れた効果が奏される。
【００６５】
ここで粉末粒子に対する解砕機構とは、一次粒子の二次的集合体としてすでに生成している適当な大きさの造粒物を部分的に解砕してその二次粒子径を低下させることのできる機構をいう。
【００６６】
つぎに図面により、本発明の製法において使用する装置を例示的に説明する。すなわち図１および図２はそれぞれ該装置の概略縦断面図である。図１において１は撹拌槽で、該撹拌槽１内にはその中央に垂直に回転軸２が配置され、該回転軸の下端部には放射状に撹拌翼３が設けられ、また上端部はモータ４に接続されている。５は液状媒体供給口である。また６は解砕機、９はモータであり、該解砕機６は移送管７および８によってそれぞれ撹拌槽１の底部および上部に接続されている。解砕機６としては、円筒体の内部でタービン翼状のカッターが回転して液状媒体を移送しつつ該媒体中に含まれているフィラー入りＰＴＦＥ粉末粒子を解砕するようにしたものを用いればよく、このような装置としてはたとえば切断と衝撃を与えるカッターとステータとを有するパイプラインホモミキサー（特殊機化工業（株）製）やデスインデグレーター（（株）小松製作所製）などが好適である。しかしてこれによって造粒を行なうには撹拌槽１内にフィラー入りＰＴＦＥ粉末を含有する液状媒体を液状媒体供給口５より仕込み、撹拌翼３によって撹拌し、撹拌と同時に、あるいは撹拌後に撹拌槽１の底部から液状媒体を移送管７によって抜出し、解砕機６を通過させることによって、形成混入せられた大粒径の粒子を解砕して移送管８より撹拌槽１内に戻す。このように撹拌槽１内での撹拌造粒と解砕機６での大粒径の粒子の解砕とを同時に、あるいは順次に、もしくは交互に行なうことによって、粒度の均一な造粒物がえられる。またこのばあい撹拌機は動かさず解砕機６のみを用いて粒子を解砕しつつ液状媒体を循環させることによっても同様の造粒粉末がえられる。その理由は解砕機による液状媒体の循環によって撹拌効果が達せられるためと考えられる。
【００６７】
図２は本発明の製法に採用可能な別の装置の実施例を示す概略縦断面図であって、撹拌槽１０内には解砕機２１（ディスパー翼）と回転軸１１に設けられた撹拌翼１２とが並置されている。１３は回転軸１１用モータ、２２は解砕機２１用モータである。撹拌翼１２は回転軸１１の下端部のボス１４に放射状にかつ螺旋状に取りつけられている。したがってこのばあいは槽内の水性媒体は撹拌翼１２によって撹拌されつつそのなかに含まれるフィラー入りＰＴＦＥ粉末が造粒され、解砕機２１によって粒子の解砕が行なわれる。
【００６８】
本発明においては、前記のごとくして調製せられたフィラー入りＰＴＦＥ粉末のスラリーを造粒用撹拌槽内に仕込んで撹拌造粒と解砕を行なうのが好ましいが、ばあいによってはフィラー入りＰＴＦＥ粉末をあらかじめ少量の水で濡らしたものを撹拌槽中で残部の液状媒体と混合したり、あるいは撹拌槽中にあらかじめ液状媒体を仕込んでおきこれにフィラー入りＰＴＦＥ粉末を投入して撹拌する方法を採用することもできる。
【００６９】
フィラー入りＰＴＦＥ粉末のスラリーは、撹拌の効果により造粒せられるが、それと同時に、もしくは造粒後に大粒子たとえば２０００μｍ以上のものが解砕機によって解砕せられ、最終的に１０００μｍを超える粗粒子を含まない、平均粒径５００μｍ以下の均一な粒度の粉末となる。
【００７０】
本発明のフィラー入りＰＴＦＥ粒状粉末の製法（１）〜（３）の具体例としては、たとえばつぎのような製法があげられる。
【００７１】
製法（１）
内容量１０リットルの造粒槽にイオン交換水１〜５リットルを入れる。これにＰＴＦＥ粉末０．９〜１．９ｋｇ、続いてフィラー０．０７５〜０．８ｋｇを添加する。
【００７２】
つぎに、特定のノニオン性界面活性剤の５％水溶液４〜２００ミリリットルを添加し、１００φのディスパー翼により２０００〜３０００ｒｐｍの撹拌速度で２〜５分間撹拌するとスラリー状態となり、さらに５〜１０分間撹拌を続ける。
【００７３】
さらに、水と液−液界面を形成する有機液体４５０〜１５００ミリリットルを添加し、１００φのディスパー翼により１０００〜２０００ｒｐｍの撹拌速度で１〜２分間撹拌して造粒する。
【００７４】
つぎに、水０．５〜５リットルを追加し、１０〜３０℃の範囲内の温度でコーン翼により６００〜９００ｒｐｍの撹拌速度で０〜３０分間整粒する。
【００７５】
つぎに、造粒槽内の温度を１５〜６０分間かけて、３７．５〜３８．０℃の範囲内の温度まで昇温し、その温度において０〜６０分間保持する。
【００７６】
なお、この温度保持工程と前記水と液−液界面を形成する有機液体の添加直後のディスパー翼による混合工程は、フィラーがたとえばガラス繊維、青銅粉末、金粉末、銀粉末、銅粉末、ステンレス鋼粉末、ステンレス鋼繊維、ニッケル粉末、ニッケル繊維などの金属繊維または金属粉末のときは、フィラーの分離の点から行なわない。
【００７７】
つぎに、撹拌を停止し、１５０メッシュのふるいを用いて造粒物と水とを分離し、この造粒物を電気炉内において、１６５℃で１６時間乾燥し、本発明のフィラー入りＰＴＦＥ粒状粉末をうる。
【００７８】
このような製法（１）では、たとえばつぎのような粉末物性や成形品物性を有している粒状粉末がえられ、とくに粒度分布がシャープであるので従来のようにふるいにかけ小粒径の粒子を取り出したり、またＰＴＦＥ粉末とフィラーとを予め混合するというような繁雑な工程が不要であるなど、従来の製法ではえられないフィラー入りＰＴＦＥ粒状粉末の製法である。
【００７９】
（フィラー入りＰＴＦＥ粒状粉末の物性）
見かけ密度：０．７０ｇ／ｃｍ³以上
０．７０ｇ／ｃｍ³より小さいと金型充填量が少なくなる。
【００８０】
流動度：６回以上
５．５回以下ではホッパー流動性の点で劣る。特に８回が好ましい。
【００８１】
安息角：４０度以下
４０度を超える粉末は流動性がわるく、好ましくない。
【００８２】
ただし、見かけ密度が０．９ｇ／ｃｍ³以上１．０ｇ／ｃｍ³未満のばあいは３８度以下、見かけ密度が１．０ｇ／ｃｍ³以上のばあいは３６度以下である。
【００８３】
通常、粉末の安息角は見かけ密度が高いほど重力の影響を受けて小さな値となる。したがって、本発明の方法によりえられる粉末の安息角も見かけ密度により変化するが、従来技術によりえられる粉末に比べて小さくなる。
【００８４】
なお、従来技術によりえられる粉末の安息角は、見かけ密度が０．７ｇ／ｃｍ³以上０．９ｇ／ｃｍ³未満のばあい４０度を超え、見かけ密度が０．９ｇ／ｃｍ³以上１．０ｇ／ｃｍ³未満のばあい３８度を超え、見かけ密度が１．０ｇ／ｃｍ³以上のばあい３６度を超える。
【００８５】

造粒後の粒状粉末がこの範囲の粒度分布を有するときは粒度が揃っているため金型内の充填ムラがなくなり、好ましい。特に１０メッシュ、２０メッシュのふるい上に存する粒状粉末がいずれも０％であるのが好ましい。
【００８６】
粒度分布Ｂ：５０重量％以上
造粒後の粒状粉末がこの粒度分布を有するときは金型の充填ムラがなくなり、好ましい。特に６０重量％以上であるのが好ましい。
【００８７】
平均粒径：５００μｍ以下
５００μｍよりも大きくなると薄肉の金型への充填ができなくなる。特に好ましくは薄肉の金型への充填性の点から１５０〜４００μｍである。
【００８８】
帯電量：５０Ｖ以下
５０Ｖを超えて帯電しているＰＴＦＥ粉末は、成形用金型だけでなく、ホッパー、フィーダーなどに静電気により付着し、結果的に流動性を阻害する。好ましくは１０Ｖ以下で、その帯電量では流動性の低下は全く生じない。
【００８９】
（成形物の物性）
引張強度：１００ｋｇｆ／ｃｍ²以上
１００ｋｇｆ／ｃｍ²より小さい成形物は機械的強度に劣る。なお、好ましくは、１５０ｋｇｆ／ｃｍ²以上であり、用途に応じて決める。
【００９０】
伸び：１００〜４００％
１００％より小さい成形物は機器への装着時や加工時に切断してしまうことがある。好ましくは１５０％以上である。
【００９１】
表面粗度：３．０μｍ以下
３．０μｍを超える成形物は表面の凹凸が大きく、好ましくない。特に好ましくは２．０μｍ以下である。
【００９２】
白色度（Ｚ値）：８０以上（ガラス繊維のばあい）本来、ＰＴＦＥ成形体は高い白色度が好まれており、商品価値の点から白色度が高いものがよい。
【００９３】
製法（２）
内容量１０リットルの造粒槽にイオン交換水１〜５リットルを入れる。これにＰＴＦＥ粉末０．９〜１．９ｋｇを添加する。
【００９４】
つぎに特定のノニオン性界面活性剤の５％水溶液４〜２００ミリリットルを添加し、１００φのディスパー翼により２０００〜３０００ｒｐｍの撹拌速度で２〜５分間撹拌すると、スラリー状態となる。
【００９５】
つぎに、フィラー０．０７５〜０．８ｋｇを添加し、１００φのディスパー翼により２０００〜４０００ｒｐｍの撹拌速度で２〜１５分間撹拌して混合する。
【００９６】
さらに水と液−液界面を形成する有機液体を添加するが、この操作以降、本発明のフィラー入りＰＴＦＥ粒状粉末をうるまでの工程は、製法（１）と同じ方法である。
【００９７】
このような製法（２）では、たとえばつぎのような粉末物性や成形品物性を有している粒状粉末がえられ、とくに粒度分布がシャープであるので従来のようにふるいにかけ小粒径の粒子を取り出したり、またＰＴＦＥ粉末とフィラーとを予め混合するというような繁雑な工程が不要であるなど、従来の製法ではえられないフィラー入りＰＴＦＥ粒状粉末の製法である。
【００９８】
（フィラー入りＰＴＦＥ粒状粉末の物性）
見かけ密度：０．７０ｇ／ｃｍ³以上
０．７０ｇ／ｃｍ³より小さいと金型充填量が少なくなる。
【００９９】
流動度：６回以上
５．５回以下ではホッパー流動性の点で劣る。特に８回が好ましい。
【０１００】
安息角：４０度以下
４０度を超える粉末は流動性がわるく、好ましくない。
【０１０１】
ただし、見かけ密度が０．９ｇ／ｃｍ³以上１．０ｇ／ｃｍ³未満のばあいは３８度以下、見かけ密度が１．０以上のばあいは３６度以下である。
【０１０２】

造粒後の粒状粉末がこの範囲の粒度分布を有するときは粒度が揃っているため金型内の充填ムラがなくなり、好ましい。特に１０メッシュ、２０メッシュのふるい上に存する粒状粉末がいずれも０％であるのが好ましい。
【０１０３】
粒度分布Ｂ：５０重量％以上
造粒後の粒状粉末がこの粒度分布を有するときは金型の充填ムラがなくなり、好ましい。特に６０重量％以上であるのが好ましい。
【０１０４】
平均粒径：５００μｍ以下
５００μｍよりも大きくなると薄肉の金型への充填ができなくなる。特に好ましくは薄肉の金型への充填性の点から１５０〜４００μｍである。
【０１０５】
帯電量：５０Ｖ以下
５０Ｖを超えて帯電しているＰＴＦＥ粉末は、成形用金型だけでなく、ホッパー、フィーダーなどに静電気により付着し、結果的に流動性を阻害する。好ましくは１０Ｖ以下で、その帯電量では流動性の低下は全く生じない。
【０１０６】
（成形物の物性）
引張強度：１００ｋｇｆ／ｃｍ²以上
１００ｋｇｆ／ｃｍ²より小さい成形物は機械的強度に劣る。なお、好ましくは、１５０ｋｇｆ／ｃｍ²以上であり、用途に応じて決める。
【０１０７】
伸び：１００〜４００％
１００％より小さい成形物は機器への装着時や加工時に切断してしまうことがある。好ましくは１５０％以上である。
【０１０８】
表面粗度：３．０μｍ以下
３．０μｍを超える成形物は表面の凹凸が大きく、好ましくない。特に好ましくは２．０μｍ以下である。
【０１０９】
白色度（Ｚ値）：８０以上（ガラス繊維のばあい）本来、ＰＴＦＥ成形体は高い白色度が好まれており、商品価値の点から白色度が高いものがよい。
【０１１０】
製法（３）
通常の懸濁重合法において重合系から取り出された平均粒径２〜３ｍｍのＰＴＦＥ粗粒子をパイプラインホモミキサーを用いて粗粉砕し、平均粒径２００〜１０００μｍ、含水率５〜３０重量％のＰＴＦＥ含水粉末をうる。
【０１１１】
つぎに、このＰＴＦＥ含水粉末を前記自由粉砕機に投入し、孔径０．１〜０．３ｍｍの多数の孔を設けたスクリーンを分級用の多孔板とし、動力２．２ｋＷ、処理量１．０〜１００ｋｇ／ｈｒの条件で湿式粉砕を行ない、平均粒径２０〜１００μｍ、含水率５〜３０％の粉末をえ、この粉末１．５７５〜２．６ｋｇをイオン交換水に添加する工程以降、本発明のフィラー入りＰＴＦＥ粒状粉末をうるまでの工程は製法（２）と同じ方法である。
【０１１２】
このような製法（３）では、たとえばつぎのような粉末物性や成形品物性を有している粒状粉末がえられ、とくに粒度分布がシャープであるので従来のようにふるいにかけ小粒径の粒子を取り出したり、またＰＴＦＥ粉末とフィラーとを予め混合するというような繁雑な工程が不要であるなど、従来の製法ではえられないフィラー入りＰＴＦＥ粒状粉末の製法である。
【０１１３】
（フィラー入りＰＴＦＥ粒状粉末の物性）
見かけ密度：０．７０ｇ／ｃｍ³以上
０．７０ｇ／ｃｍ³より小さいと金型充填量が少なくなる。
【０１１４】
流動度：６回以上
５．５回以下ではホッパー流動性の点で劣る。特に８回が好ましい。
【０１１５】
安息角：４０度以下
４０度を超える粉末は流動性がわるく、好ましくない。
【０１１６】
ただし、見かけ密度が０．９ｇ／ｃｍ³以上１．０ｇ／ｃｍ³未満のばあいは３８度以下、見かけ密度が１．０以上のばあいは３６度以下である。
【０１１７】

造粒後の粒状粉末がこの範囲の粒度分布を有するときは粒度が揃っているため金型内の充填ムラがなくなり、好ましい。特に１０メッシュ、２０メッシュのふるい上に存する粒状粉末がいずれも０％であるのが好ましい。
【０１１８】
粒度分布Ｂ：５０重量％以上
造粒後の粒状粉末がこの粒度分布を有するときは金型の充填ムラがなくなり、好ましい。特に６０重量％以上であるのが好ましい。
【０１１９】
平均粒径：５００μｍ以下
５００μｍよりも大きくなると薄肉の金型への充填ができなくなる。特に好ましくは薄肉の金型への充填性の点から１５０〜４００μｍである。
【０１２０】
（成形物の物性）
引張強度：１００ｋｇｆ／ｃｍ²以上
１００ｋｇｆ／ｃｍ²より小さい成形物は機械的強度に劣る。なお、好ましくは、１５０ｋｇｆ／ｃｍ²以上であり、用途に応じて決める。
【０１２１】
伸び：１００〜４００％
１００％より小さい成形物は機器への装着時や加工時に切断してしまうことがある。好ましくは１５０％以上である。
【０１２２】
表面粗度：３．０μｍ以下
３．０μｍを超える成形物は表面の凹凸が大きく、好ましくない。特に好ましくは２．０μｍ以下である。
【０１２３】
白色度（Ｚ値）：８０以上（ガラス繊維のばあい）本来、ＰＴＦＥ成形体は高い白色度が好まれており、商品価値の点から白色度が高いものがよい。
【０１２４】
本発明のフィラー入りＰＴＦＥ粒状粉末の製法における条件としては、たとえばつぎのようなものが好ましくあげられる。
【０１２５】

【０１２６】
より好ましくは

【０１２７】

【０１２８】
より好ましくは

【０１２９】

【０１３０】
より好ましくは

【０１３１】
【実施例】
つぎに、本発明を実施例に基づいてさらに具体的に説明するが、本発明はこれらのみに限定されない。
【０１３２】
実施例１［製法（１）］
内容量１０リットルの造粒槽にイオン交換水１．５リットルを入れ、さらに粉砕後の平均粒径が３１μｍのＰＴＦＥ粉末（ダイキン工業（株）製ポリフロンＭ−１２、ＰＴＦＥホモポリマー）１．２７５ｋｇ（ドライ基準）と、予めアミノシランカップリング剤で撥水処理されたガラス繊維（日本電気硝子（株）製ＥＰＧ４０Ｍ−１０Ａ、平均直径１２μｍ、平均繊維長８０μｍ）０．２２５ｋｇとを順次添加する。
【０１３３】
つぎに特定のノニオン性界面活性剤としてポリプロピレングリコールのエチレンオキサイドブロックポリマー（ポリオキシプロピレンセグメントの分子量１０００、ポリオキシエチレンセグメントの分子量６６７。日本油脂（株）製のプロノン＃１０４）の５重量％水溶液９０ｍｌを添加する。
【０１３４】
つぎに、１００φのディスパー翼を用いて３０００ｒｐｍの撹拌速度で２分間撹拌するとＰＴＦＥ粉末とフィラーが、水に濡れ、粘度１０〜１０００ｃｐｓの粘稠状のスラリー状態となり、この状態でさらに３分間撹拌して混合する。
【０１３５】
つぎに、水と液−液界面を形成する有機液体（塩化メチレン）７５０ｍｌを添加し、１００φのディスパー翼を用いて１５００〜２０００ｒｐｍの撹拌速度で１〜２分間撹拌して造粒する。
【０１３６】
つぎに、水４．５リットルを追加し、コーン翼を用いて８００ｒｐｍでの撹拌下、２５℃±２℃で１５分間整粒する。
【０１３７】
つぎに、槽内温度を２０分かけて３８℃まで昇温して撹拌を停止し、１５０メッシュのふるいを用いて造粒物と水とを分離し、えられた造粒物を電気炉内において、１６５℃で１６時間乾燥して、本発明のフィラー入りＰＴＦＥ粒状粉末をえ、つぎの試験を行なった。
【０１３８】
見かけ密度：ＪＩＳ Ｋ ６８９１−５．３に準じて測定した。
【０１３９】
粉砕後の平均粒径（一次粒子の粒径）
ウェットシーブ法：ＪＩＳ標準ふるい２０メッシュ（ふるい目の開き８４０μｍ）、２５０メッシュ（ふるい目の開き６２μｍ）、２７０メッシュ（ふるい目の開き５３μｍ）、３２５メッシュ（ふるい目の開き４４μｍ）および４００メッシュ（ふるい目の開き３７μｍ）使用される。まず、２０メッシュふるいを２５０メッシュふるいの上に重ねる。５ｇの粉末試料を２０メッシュふるいの上に乗せて、シャワー霧吹きをを用いて約３リットル／ｍ²の割合で約３０秒間、四塩化炭素を霧吹くことにより、下方ふるい上に注意深く洗い落とす。試料が完全に洗い落とされたら、上方ふるいを取り除き、下方ふるいをまんべんなく約４分間霧吹く。その後、下方ふるいを空気乾燥し、このふるいの上に保留された乾燥粉末の重量を測定する。この一連の操作を２０メッシュふるいと他の３つの小メッシュふるいの１つとを用いて各々新しい５ｇの粉末試料について繰り返す。累積重量百分率値をうるために各ふるい上に保留される粉末の重量に２０を掛け、つぎにこれらの数値を対数確率紙上にふるい目の開きに対してプロットする。これらの点を直線で結び、累積百分率５０（ｄ₅₀）および８４（ｄ₃₄）に相当する粒径を読み取り、次式によってウェットシーブサイズ（ｄ_WS）を計算して求める。
【０１４０】
【数１】

流動度：特開平３−２５９９２５号公報記載の方法に準じて測定した。
【０１４１】
すなわち、測定装置としては、図３（特開平３−２５９９２５号公報記載の第３図に対応）に示されるごとく支持台４２に中心線を一致させて支持した上下のホッパー３１および３２を用いる。上部ホッパー３１は、入口３３の直径７４ｍｍ、出口３４の直径１２ｍｍ、入口３３から出口３４までの高さ１２３ｍｍで、出口３４に仕切板３５があり、これによって中の粉末を保持したり落したりすることが適宜できる。下部ホッパー３２は入口３６の直径７６ｍｍ、出口３７の直径１２ｍｍ、入口３６から出口３７までの高さ１２０ｍｍで、上部ホッパーと同様出口３７に仕切板３８が設けられている。上部ホッパーと下部ホッパーとの距離は各仕切板の間が１５ｃｍとなるように調節されている。なお図３中３９および４０はそれぞれ各ホッパーの出口カバーであり、４１は落下した粉末の受器である。
【０１４２】
流動性の測定は被測定粉末約２００ｇを２３．５〜２４．５℃に調温した室内に４時間以上放置し、１０メッシュ（目の開き１６８０ミクロン）でふるったのち、同温度で行なわれる。
【０１４３】
(Ｉ)まず、容量３０ｃｃのコップに丁度１杯の被測定粉末を上部ホッパー３１へ入れたのち、ただちに仕切板３５を引抜いて粉末を下部ホッパーへ落す。落ちないときは針金でつついて落す。粉末が下部ホッパー３２に完全に落ちてから１５±２秒間放置したのち下部ホッパーの仕切板３８を引抜いて粉末が出口３７から流れ落ちるかどうかを観察し、このとき８秒以内に全部流れ落ちたばあいを落ちたものと判定する。
【０１４４】
(II)以上と同じ測定を３回くり返して落ちるかどうかをみ、３回のうち２回以上流れ落ちたばあいは流動性「良」と判定し、１回も落ちないばあいは流動性「不良」と判定する。３回のうち１回だけ流れ落ちたばあいは、さらに２回同じ測定を行ない、その２回とも落ちたばあいは結局その粉末の流動性は「良」と判定し、それ以外のばあいは流動性「不良」と判定する。
【０１４５】
(III)以上の測定で流動性「良」と判定された粉末については、つぎの同じ容量３０ｃｃのコップ２杯の粉末を上部ホッパーへ入れて前述したところと同様にして測定を行ない、結果が流動性「良」とでたときは順次粉末の杯数を増加してゆき、「不良」となるまで続け、最高８杯まで測定する。各測定の際には、前回の測定で下部ホッパーから流出した粉末を再使用してもよい。
【０１４６】
(IV)以上の測定でＰＴＦＥ粉末は使用量が多いほど流れ落ちにくくなる。
【０１４７】
そこで流動性「不良」となったときの杯数から１を引いた数をもってその粉末の「流動度」と定める。
【０１４８】
造粒パウダーの粒度分布Ａおよび平均粒径：上から順に１０、２０、３２、４８および６０メッシュ（インチメッシュ）の標準ふるいを重ね、１０メッシュふるい上にＰＴＦＥ粒状粉末をのせ、ふるいを振動させて下方へ順次細かいＰＴＦＥ粒状粉末粒子を落下させ、各ふるい上に残留したＰＴＦＥ粒状粉末の割合を％で求めたのち、対数確率紙上に各ふるいの目の開き（横軸）に対して残留割合の累積パーセント（縦軸）を目盛り、これらの点を直線で結び、この直線上で割合が５０％となる粒径を求め、この値を平均粒径とする。
【０１４９】
粒度分布Ｂ：平均粒径の０．７〜１．３倍の直径を有する粒子の全粒子に対する重量割合であり、平均粒径に０．７倍あるいは１．３倍の値を乗ずることによって算出し、累積曲線中にその点を書込むことによって重量割合を求める。
【０１５０】
引張強度（以下、ＴＳともいう）および伸び（以下、ＥＬともいう）：内径１００ｍｍの金型に２５ｇの粉末を充填し、約３０秒間かけて最終圧力が約５００ｋｇ／ｃｍ²となるまで徐々に圧力を加え、さらに２分間その圧力に保ち予備成形体をつくる。金型から予備成形体を取り出し、３６５℃に保持してある電気炉へこの予備成形体を入れ、３時間焼成後、取り出して焼成体をうる。この焼成体からＪＩＳダンベル３号で試験片を打ち抜き、ＪＩＳ Ｋ６８９１−５８に準拠して、総荷重５００ｋｇのオートグラフを用い、引張速度２００ｍｍ／分で引張り、破断時の応力と伸びを測定する。
【０１５１】
安息角：ホソカワミクロン製パウダーテスターを用いて測定した。
【０１５２】
帯電量：Ｉｏｎ ｓｙｓｔｅｍｓ，Ｉｎｃ．製ハンディ静電測定器ＳＦＭ７７５を用いて測定する。
【０１５３】
白色度（Ｚ値）：造粒粉末２００ｇを直径５０ｍｍの金型に充填し、成形圧力５００ｋｇ／ｃｍ²で５分間保持し、得られた予備成形品（直径約５０ｍｍ、高さ約５０ｍｍ）を室温から５０℃／ｈｒの昇温速度で３６５℃まで昇温し、３６５℃で５．５時間保持した後、５０℃／ｈｒで冷却した成形品を、端から約２５ｍｍ（中心部分）のところで、旋盤で横割りし、切り出した部分の中心部のＺ値を国際照明委員会の定めるＸＹＺ系のＺ値測定法に基づいて測定した。
【０１５４】
表面粗度：粉末２１０ｇを直径５０ｍｍの金型に充填し、成形圧力５００ｋｇ／ｃｍ²で５分間保持し、えられた予備成形品を５０℃／ｈｒの昇温速度で室温 から３６５℃まで昇温し、３６５℃で５．５時間保持したのち、５０℃／ｈｒ で冷却する。えられた成形品の上部表面を東京精密機械（株）製の表面あらさ 測定機を用い、ＪＩＳ Ｂ ０６０１に記載の中心線平均粗さ（Ｒａ）法に従
い測定した。
【０１５５】
なお、実施例１でえられたフィラー入りＰＴＦＥ粒状粉末については、つぎの方法により該粉末中の粒子の写真撮影を行なった。
【０１５６】
粒子の形状：ソニー（株）製光学顕微鏡ビデオマイクロスコープを用いて拡大倍率１００倍または２００倍の像について写真撮影を行なった。
【０１５７】
結果を表１ならびに図４（１００倍）および図５（２００倍）に示す。
【０１５８】
実施例２〜３
実施例１において用いる特定のノニオン性界面活性剤の量を表１に示す量としたほかは実施例１と同様にしてフィラー入りＰＴＦＥ粉末を製造し、実施例１と同様にして各種物性を調べた。結果を表１に示す。
【０１５９】
実施例４［製法（２）］
内容量１０リットルの造粒槽にイオン交換水１．５リットルを入れ、さらに粉砕後の平均粒径が３１μｍのＰＴＦＥ粉末（ダイキン工業（株）製ポリフロンＭ−１２、ＰＴＦＥホモポリマー）１．２７５ｋｇ（ドライ基準）を添加する。
【０１６０】
つぎに、特定のノニオン性界面活性剤として、ポリプロピレングリコールのエチレンオキサイドブロックポリマー（プロノン＃１０４）の５％水溶液９０ｍｌを添加する。
【０１６１】
ついで、１００φのディスパー翼を用いて３０００ｒｐｍの回転数で２分間撹拌するとＰＴＦＥ粉末が水に濡れ、粘度１０〜１０００ｃｐｓの粘稠状のスラリー状態となる。
【０１６２】
さらに、予めアミノシランカップリング剤で撥水処理されたガラス繊維（実施例１と同じもの）０．２２５ｋｇを添加し、１００φのディスパー翼を用いて３０００ｒｐｍの回転数で２分間撹拌するとガラス繊維も水に濡れ、粘度１０〜１０００ｃｐｓの粘稠状のスラリー状態となる。この状態でさらに３分間撹拌して混合する。
【０１６３】
つぎに、水と液−液界面を形成する有機液体（塩化メチレン）７５０ｍｌを添加し、１００φのディスパー翼を用いて１５００〜２０００ｒｐｍの撹拌速度で１〜２分間撹拌して造粒する。
【０１６４】
つぎに、水４．５リットルを追加し、コーン翼を用いて８００ｒｐｍでの撹拌下、２５℃±２℃で１５分間整粒する。
【０１６５】
つぎに、槽内温度を２０分かけて３８℃まで昇温して撹拌を停止し、１５０メッシュのふるいを用いて造粒物と水とを分離し、えられた造粒物を電気炉内において、１６５℃で１６時間乾燥して、本発明のフィラー入りＰＴＦＥ粒状粉末をえ、実施例１と同様の試験を行なった。結果を表１に示す。
【０１６６】
なお、えられたフィラー入りＰＴＦＥ粉末について実施例１と同様にして顕微鏡で観察し、写真撮影した。撮影した写真（２００倍）を図６に示す。
【０１６７】
実施例５［製法（３）］
内容量２０００リットルの撹拌機付きステンレススチール製のオートクレーブに脱酸素した純水１６００リットルを入れ、内部の空気をチッ素で置換し、ついでテトラフルオロエチレンで置換したのち、内部の温度を１０℃に保ちつつ、内部の圧力が６気圧になるまでテトラフルオロエチレンを圧入し、重合開始剤として（ＮＨ₄）₂Ｓ₂Ｏ₂およびＦｅＳＯ₄を添加して撹拌しながらテトラフルオロエチレンの重合を行なう。重合に伴って圧力が低下するので、内部の圧力が６気圧に保たれるように、テトラフルオロエチレンを連続的に追加する。４時間後に撹拌を中止し、テトラフルオロエチレンを回収したのち内容物を取り出す。生成重合体である平均粒径２〜３ｍｍのＰＴＦＥ粗粒子をＴ．Ｋ．パイプラインホモミキサー２Ｓ型機（特殊機化工業（株）製）で粗粉砕して、平均粒径約４００μｍのＰＴＦＥ粗粉末をうる。
【０１６８】
このＰＴＦＥ粗粉末を、乾燥せず約２５重量％の水を含んだまま自由粉砕機Ｍ−２型（奈良機械（株）製）に投入し、湿式粉砕を行なった。このとき、孔径０．２５ｍｍの多数の孔を設けたスクリーンを分級用の多孔板として用い、動力２．２ＫＷ、処理量３８ｋｇ／ｈｒで湿式微粉砕し、平均粒径３６μｍのＰＴＦＥ粉末をえた。
【０１６９】
内容量１０リットルの造粒槽にイオン交換水１．５リットルを入れ、さらに湿式微粉砕した平均粒径３６μｍの前記ＰＴＦＥ粉末１．２７５ｋｇ（ドライ基準）を添加する。
【０１７０】
つぎに、特定のノニオン性界面活性剤として、ポリプロピレングリコールのエチレンオキサイドブロックポリマー（プロノン＃１０４）の５％水溶液９０ｍｌを添加する。
【０１７１】
ついで、１００φのディスパー翼を用いて３０００ｒｐｍの回転数で２分間撹拌するとＰＴＦＥ粉末が水に濡れ、粘度１０〜１０００ｃｐｓの粘稠状のスラリー状態となる。
【０１７２】
さらに、予めアミノシランカップリング剤で撥水処理されたガラス繊維（実施例１と同じもの）０．２２５ｋｇを添加し、１００φのディスパー翼を用いて３０００ｒｐｍの回転数で２分間撹拌するとガラス繊維も水に濡れ、粘度１０〜１０００ｃｐｓの粘稠状のスラリー状態となる。この状態でさらに３分間撹拌して混合する。
【０１７３】
つぎに、水と液−液界面を形成する有機液体（塩化メチレン）７５０ｍｌを添加し、１００φのディスパー翼を用いて１５００〜２０００ｒｐｍの撹拌速度で１〜２分間撹拌して造粒する。
【０１７４】
つぎに、水４．５リットルを追加し、コーン翼を用いて８００ｒｐｍでの撹拌下、２５℃±２℃で１５分間整粒する。
【０１７５】
つぎに、槽内温度を２０分かけて３８℃まで昇温して撹拌を停止し、１５０メッシュのふるいを用いて造粒物と水とを分離し、えられた造粒物を電気炉内において、１６５℃で１６時間乾燥して、本発明のフィラー入りＰＴＦＥ粒状粉末をえ、実施例１と同様の試験を行なった。結果を表１に示す。
【０１７６】
なお、えられたフィラー入りＰＴＦＥ粉末について実施例１と同様にして顕微鏡で観察し、写真撮影した。撮影した写真（２００倍）を図７に示す。
【０１７７】
【表１】

なお、表１の粒度分布Ａ欄の１０ｏｎは１０メッシュのふるい上に、２０ｏｎは２０メッシュのふるい上に、３２ｏｎは３２メッシュのふるい上に、４８ｏｎは４８メッシュのふるい上に、６０ｏｎは６０メッシュのふるい上、８３ｏｎは８３メッシュのふるいの上にいずれも残存する粒子の割合を示しており、８３ｐａｓｓは８３メッシュのふるいを通過する粒子の割合を示している。
【０１７８】
表１の結果から明らかなように、本発明のいずれの製法によっても、えられるフィラー入りＰＴＦＥ粒状粉末は、見かけ密度が大きく、とくに小粒径で粒度分布がシャープであり、帯電量が小さく、小粒径であるにもかかわらず優れた流動性を有しており、また該粒状粉末からえられる成形品は、引張強度、伸びに優れ、表面粗度が小さい。
【０１７９】
また、本発明の製法は、特定の界面活性剤の添加量により、フィラー入りＰＴＦＥ粒状粉末の平均粒径および粒度分布を制御できることがわかる。
【０１８０】
また、白色または透明のフィラーを用いるときは、えられる成形品の白色度（Ｚ値）は８０以上、さらには９５以上と、従来にない高いものとなる。
【０１８１】
図４〜５は実施例１で、また図６および図７はそれぞれ実施例４および５でえられた本発明のフィラー入りＰＴＦＥ粒状粉末中の粒子の粒子構造を示す光学顕微鏡写真であり、これらの図（写真）から明らかなように、本発明のフィラー入りＰＴＦＥ粒状粉末中の粒子は、ほぼ球形であることがわかる。
【０１８２】
本発明のフィラー入りＰＴＦＥ粒状粉末が、その粒子の平均粒径が小さいにもかかわらず、粉末流動性に著しく優れているのは、たとえばこのようにその粒子の形状がほぼ球形であることが考えられる。
【０１８３】
【発明の効果】
本発明のフィラー入りＰＴＦＥ粒状粉末は見かけ密度が大きく、その粒子の大部分はほぼ球形であり平均粒径が小さくて粒度分布がシャープであり、帯電量が小さく、平均粒径が小さいにもかかわらず粉末流動性に優れ、粒状粉末からえられる成形品は、引張強度、伸びに優れ表面粗度が小さく白色度の高いものである。
【０１８４】
また、本発明の製法（１）〜（３）は、前記のような優れた物性を有するフィラー入りＰＴＦＥ粒状粉末を提供できるとともに、とくに特定のノニオン性界面活性剤の量により平均粒径および粒度分布を制御でき、粒度分布がシャープな粒状粉末がえられる製法である。
【図面の簡単な説明】
【図１】本発明の製法に使用できる造粒装置の概略縦断面図である。
【図２】本発明の製法に使用できる別の造粒装置の概略断面図である。
【図３】本発明において粒状粉体の流動性を調べるために用いた装置の概略説明図である。
【図４】実施例１でえられた本発明のフィラー入りＰＴＦＥ粒状粉末中の粒子の粒子構造を示す光学顕微鏡写真（倍率：１００倍）である。
【図５】実施例１でえられた本発明のフィラー入りＰＴＦＥ粒状粉末中の粒子の粒子構造を示す光学顕微鏡写真（倍率：２００倍）である。
【図６】実施例４でえられた本発明のフィラー入りＰＴＦＥ粒状粉末中の粒子の粒子構造を示す光学顕微鏡写真（倍率：２００倍）である。
【図７】実施例５でえられたフィラー入りＰＴＦＥ粒状粉末中の粒子の粒子構造を示す光学顕微鏡写真（倍率：２００倍）である。
【符号の説明】
１ 撹拌槽
３ 撹拌翼
６ 解砕機
１０ 撹拌槽
１２ 撹拌翼
２１ 解砕機[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a filler-containing polytetrafluoroethylene granular powder and a method for producing the same.
[0002]
[Prior art]
Conventionally, as a method for obtaining a filler-filled PTFE granular powder by stirring and granulating a mixture of a filler and polytetrafluoroethylene (PTFE) powder in water, for example, Japanese Patent Publication No. 43-8611 and Japanese Patent Publication No. 44-22619. No. 4, JP-B 48-37576, JP-B 49-17855, JP-B 56-8044, JP-B 57-18730 and the like.
[0003]
However, in the production methods described in the above-mentioned publications, filler-containing PTFE granular powder having a small particle size and a sharp particle size distribution has not been obtained.
[0004]
For this reason, when trying to obtain small articles such as rubber band seal rings, thin molded articles, and molded articles with low surface roughness, the filler-filled PTFE granular powder is sieved and only small particles are taken out. There is a problem that a complicated and uneconomical method such as molding or cutting the obtained molded body has to be used.
[0005]
Moreover, the granular powder which has the outstanding powder fluidity | liquidity cannot be obtained only by grind | pulverizing the PTFE granular powder containing a filler.
[0006]
In Japanese Examined Patent Publication No. 60-21694, a filler is obtained by granulating a PTFE powder and a filler previously surface-treated with an aminosilane compound in water in the presence of a water-insoluble organic liquid and an anionic surfactant. Although a production method for obtaining filled PTFE granular powder has been proposed, it is not satisfactory in terms of the apparent density of the filled PTFE granular powder and the tensile strength of a molded product obtained from the filled PTFE granular powder.
[0007]
Furthermore, in the manufacturing method as described above, there are problems such as a long process, a complicated process in which a filler and PTFE powder are mixed in advance, and a high cost.
[0008]
[Problems to be solved by the invention]
As a result of diligent examination of the above-mentioned problems, PTFE powder and filler are mixed in a slurry state in water in the presence of a surfactant, and further stirred in the presence of an organic liquid that forms a liquid-liquid interface with water. It was found that the above-mentioned problems can be solved by granulation.
[0009]
In the granulation method (hereinafter, also referred to as “slurry granulation method”), the present inventors conducted further research to obtain a granular powder having further excellent powder characteristics and physical properties. It has been found that when a specific nonionic surfactant is used, a molded product having a small charge amount and high whiteness (Z value) can be provided.
[0010]
That is, the objective of this invention is providing the PTFE granular powder with a filler excellent in workability, and its manufacturing method. In particular, molded products with high apparent density, small average particle size, sharp particle size distribution, small charge amount, excellent powder physical properties such as powder flowability, and excellent molded product physical properties such as whiteness and elongation. An object of the present invention is to provide a filler-filled PTFE granular powder and a method for producing the same.
[0011]
[Means for Solving the Problems]
In the present invention, when agglomerating the polytetrafluoroethylene powder and filler obtained by suspension polymerization in water, the powder and the filler are separately put into water without being mixed in advance, After stirring and mixing in the presence of a nonionic surfactant having a hydrophobic segment composed of 3 to 4 poly (oxyalkylene) units and a hydrophilic segment composed of poly (oxyethylene) units, and then into a slurry state, The present invention relates to a method for producing a filler-filled polytetrafluoroethylene granular powder, which is granulated by stirring in the presence of an organic liquid that forms a liquid-liquid interface with water.
[0012]
Further, in the present invention, when the polytetrafluoroethylene powder obtained by the suspension polymerization method and the filler are granulated by stirring in water, the powder is put into water to obtain a poly (oxyalkylene) having 3 to 4 carbon atoms. The mixture is agitated in the presence of a nonionic surfactant having a hydrophobic segment composed of units and a hydrophilic segment composed of poly (oxyethylene) units to form a slurry. It is related with the manufacturing method of the filler-containing polytetrafluoroethylene granular powder characterized by stirring and granulating in presence of the organic liquid which forms a liquid-liquid interface.
[0013]
The present invention also provides a wet pulverization of the polymerized polytetrafluoroethylene water-containing powder without going through a drying step when the polytetrafluoroethylene powder obtained by the suspension polymerization method and the filler are granulated by stirring in water. And then stirred in the presence of a nonionic surfactant having a hydrophobic segment composed of a poly (oxyalkylene) unit having 3 to 4 carbon atoms and a hydrophilic segment composed of a poly (oxyethylene) unit. Filled with polytetrafluoroethylene particles filled with filler, mixed in a slurry state, and then stirred and granulated in the presence of an organic liquid that forms a liquid-liquid interface with water It relates to a method for producing powder.
[0014]
The present invention also provides a means for crushing the granular powder obtained by the granulation by adding a means for the agitation in the agitation granulation in each of the above production methods, and using the agitation and pulverization in combination. It relates to a method for producing filler-containing polytetrafluoroethylene granular powder.
[0015]
Furthermore, in the present invention, the apparent density of the filler-containing polytetrafluoroethylene granular powder obtained by any one of the above-mentioned production methods is 0.7 g / cm.^ThreeThe fluidity (defined later) of the granular powder is 6 times or more and the charge amount is 50 V or less, or the apparent density is 0.7 g / cm.^Three0.9 g / cm^ThreeIf the angle is less than 40 degrees, the angle of repose is 40 degrees or less, 0.9 g / cm^Three1.0 g / cm^ThreeIf the angle is less than 38 °, the angle of repose is 38 degrees or less, 1.0 g / cm.^ThreeThe above case relates to a filler-filled PTFE granular powder having an angle of repose of 36 ° or less, an average particle size of 500 μm or less, and a charge amount of 50 or less.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The production method of the present invention comprises a PTFE powder (hereinafter including PTFE water-containing powder unless otherwise specified) and a filler, a hydrophobic segment comprising poly (oxyalkylene) units having 3 to 4 carbon atoms, and a poly (oxyethylene) unit. It has the greatest feature in stirring in water and mixing in a slurry state in the presence of a nonionic surfactant having a hydrophilic segment consisting of (hereinafter also referred to as “specific nonionic surfactant”) For example, a complicated process of mixing PTFE powder and filler in advance as in the prior art is not required.
[0017]
That is, the production method of the present invention is:
(1) When the polytetrafluoroethylene powder and filler obtained by suspension polymerization are granulated by stirring in water, the powder and filler are separately poured into water without being mixed in advance, and a specific nonion In the presence of a surfactant, the mixture is mixed to form a slurry, and further granulated by stirring in the presence of an organic liquid that forms a liquid-liquid interface with water. A process for producing a fluoroethylene granular powder (hereinafter also referred to as “production process (1)”),
(2) When granulating polytetrafluoroethylene powder and filler obtained by suspension polymerization in water, the powder is put into water and stirred in the presence of a specific nonionic surfactant. The slurry is made into a slurry state, the filler is added to and mixed with the slurry, and the mixture is further granulated by stirring in the presence of an organic liquid that forms a liquid-liquid interface with water. Production method of granular powder (hereinafter also referred to as “Production method (2)”) and
(3) When the polytetrafluoroethylene powder obtained by suspension polymerization and the filler are granulated by stirring in water, the polytetrafluoroethylene hydrous powder as the powder is wet pulverized without going through a drying step. The mixture is stirred in the presence of a specific nonionic surfactant to form a slurry, and after adding a filler to the slurry and mixing, the presence of an organic liquid that forms a liquid-liquid interface with water It is a manufacturing method (hereinafter, also referred to as “manufacturing method (3)”) of a filler-filled polytetrafluoroethylene granular powder, which is granulated by stirring under.
[0018]
In the production method (1), it is not necessary to mix the PTFE powder and the filler in advance. For example, the PTFE powder is charged first, or the filler is charged first or simultaneously. And how to do it.
[0019]
In the production method (1), PTFE powder and filler are poured into water, added with a specific nonionic surfactant, and then stirred, so that the PTFE powder and filler get wet with water and stirring is continued. It becomes the state of a uniform mixture of powder, filler and water, that is, a slurry state. This is usually a viscous material having a viscosity of 10 to 1000 cps.
[0020]
After becoming a slurry, by adding and stirring an organic liquid that forms a liquid-liquid interface with water, granulation starts in the liquid droplets, but certain nonionic interfaces that already exist Due to the action of the activator, the droplets can remain smaller and more spherical.
[0021]
In the production method (2), the PTFE powder is put into water and then a specific nonionic surfactant is added, so that the PTFE powder becomes wet and becomes a uniform mixture with water by stirring. After entering the slurry state, a uniform mixture (viscosity of 10 to 1000 cps) of PTFE powder, filler and water can be obtained by further charging and stirring.
[0022]
After adding the filler, slurry granulation may be performed in the same manner as in production method (1).
[0023]
In the production method (3), as described later, the PTFE water-containing powder is wet-ground without going through the drying step, put into water, added with a specific nonionic surfactant, and started to stir to become the slurry state. By adding the filler in the same manner as in the production method (2), the PTFE powder and the filler are uniformly mixed.
[0024]
After adding the filler, slurry granulation may be performed in the same manner as in production method (1).
[0025]
In the production method of the present invention, a specific nonionic surfactant may be added to water in advance.
[0026]
The PTFE powder used in the present invention is obtained by an ordinary suspension polymerization method, for example, from a tetrafluoroethylene (TFE) homopolymer, a copolymer capable of copolymerization with TFE, and a copolymer of TFE. The average particle size after pulverization is preferably 200 μm or less and preferably 50 μm or less, but the lower limit is determined by the pulverizer and the pulverization technique, and the moisture content after drying is 0.1% by weight or less. The powder is preferably 0.02% by weight or less.
[0027]
Examples of the pulverizer used for the pulverization include pulverizers such as a hammer mill, a pulverizer having bladed rotors, an airflow energy type pulverizer, and an impact pulverizer.
[0028]
In the present invention, a PTFE-containing water powder can be used as the PTFE powder. For example, PTFE coarse particles having an average particle diameter of 2 to 3 mm obtained by the same suspension polymerization method as the PTFE powder and taken out from the polymerization system are used. For example, a PTFE water-containing powder having a mean particle diameter of 200 to 1000 μm and a water content of 5 to 30% by weight is exemplified by using a pipeline homomixer. Next, this PTFE water-containing powder was put into a free crusher described later, and a screen provided with a large number of holes having a pore diameter of 0.1 to 0.3 mm was used as a perforated plate for classification, power 2.2 kW, throughput 1. Wet pulverization is carried out under conditions of 0 to 100 kg / hr to obtain a powder having an average particle diameter of 20 to 100 μm and a moisture content of 5 to 30% by weight. When such a moisture-containing powder is used, the PTFE powder is obtained. The drying step is not necessary.
[0029]
Examples of the monomer that can be copolymerized with TFE include, for example, formula (I):
CF₂= CF-OR_f        (I)
[Wherein R_fIs a perfluoroalkyl group having 1 to 10 carbon atoms, a perfluoro (alkoxyalkyl) group having 4 to 9 carbon atoms, formula (II):
[0030]
[Chemical 1]

(Wherein m is 0 or an integer of 1 to 4) or the formula (III):
[0031]
[Chemical 2]

(Wherein n represents an integer of 1 to 4), and the like.
[0032]
The perfluoroalkyl group has 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, and is excellent in creep resistance while maintaining the property that it cannot be melt-molded by setting the carbon number within this range. The effect is obtained.
[0033]
Examples of the perfluoroalkyl group include perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, etc., but perfluoropropyl is preferred in terms of creep resistance and monomer cost. Is preferred.
[0034]
By setting the polymerization ratio of the monomer copolymerizable with TFE to a ratio in the range of 1.0 to 0.001 mol%, an effect of excellent creep resistance can be obtained.
[0035]
By making the average particle size of the particles of the PTFE powder or the PTFE water-containing powder within the above range, the granular powder obtained by granulation is excellent in handleability, that is, powder flowability and apparent density, and can be molded. The effect is that the physical properties are excellent.
[0036]
Among the fillers used in the present invention, in the case of a hydrophilic filler, the filler is hydrophilic and easily moves to the aqueous phase, and it is difficult to uniformly mix with the PTFE powder. That is, all of the filler used is mixed with the PTFE powder. There is a problem that the powder cannot be obtained and a part thereof remains in the treated water. This phenomenon is called filler separation.
[0037]
In order to cope with this problem, a method is adopted in which the hydrophilic filler is preliminarily hydrophobized and the surface activity is lowered to bring it close to the surface activity of the particles of the PTFE powder, followed by stirring in water. .
[0038]
Known compounds for such surface treatment include (a) silane having an amino functional group, silane having a phenyl group, and / or soluble silicone (Japanese Patent Laid-Open No. 51-548). (B) hydrocarbon monocarboxylic acid having 12 to 20 carbon atoms (Japanese Patent Publication No. 48-37576), (c) aliphatic There are chromium complex compounds of carboxylic acids (Japanese Patent Publication No. 48-37576), (d) silicone (Japanese Patent Laid-Open No. 53-139660), and (e) a method of coating a hydrophilic filler with PTFE itself (Special Japanese Laid-Open Patent Publication No. 51-121417) is also known.
[0039]
As a more specific compound for the surface treatment of the hydrophilic filler described above, for example, γ-aminopropyltriethoxysilane (H₂N (CH₂)_ThreeSi (OC₂H_Five)_Three), M- or p-aminophenyltriethoxysilane (H₂N-C₆H_Four-Si (OC₂H_Five)_Three), Γ-ureidopropyltriethoxysilane (H₂NCONH (CH₂)_ThreeSi (OC₂H_Five)_ThreeN- (β-aminoethyl) -γ-aminopropyltrimethoxysilane (H₂N (CH₂)₂NH (CH₂)_ThreeSi (OCH_Three)_Three), N- (β-aminoethyl) -γ-amino-propylmethyldimethoxysilane (H₂N (CH₂)₂NH (CH₂)_ThreeSiCH_Three(OCH_Three)₂) And the like. In addition to these compounds, organic compounds such as phenyltrimethoxysilane, phenyltriethoxysilane, p-chlorophenyltrimethoxysilane, p-bromomethylphenyltrimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenylsilanediol, etc. Examples thereof include silane compounds.
[0040]
In addition, when the filler has water repellency, it can be used as it is.
[0041]
Examples of the filler include glass fiber, graphite powder, bronze powder, gold powder, silver powder, copper powder, stainless steel powder, stainless steel fiber, nickel powder, nickel fiber and other metal fibers or metal powder, molybdenum disulfide powder, Mica fluoride powder, coke powder, carbon fiber, boron nitride powder, inorganic fiber such as carbon black or inorganic powder, aromatic heat resistant resin powder such as polyoxybenzoyl polyester, polyimide powder, tetrafluoroethylene-perfluoro One type or two or more types of fillers such as (alkyl vinyl ether) copolymer (PFA) powder and organic powder such as polyphenylene sulfide powder may be mentioned, but the invention is not limited thereto.
[0042]
When two or more fillers are used, for example, glass fiber and graphite powder, glass fiber and molybdenum disulfide powder, bronze powder and molybdenum disulfide powder, bronze powder and carbon fiber, graphite powder and coke powder, graphite powder and aromatic A combination of a heat resistant resin powder, carbon fiber and an aromatic heat resistant resin powder is preferable, and the mixing method may be a wet method or a dry method.
[0043]
The PTFE granular powder with filler of the present invention has a high whiteness of the PTFE portion. Therefore, when using a white or transparent filler such as glass fiber, boron nitride powder, titanium oxide powder, etc., an unprecedented high whiteness A molded product of degree (Z value) is obtained.
[0044]
In the case of powder, the filler preferably has an average particle diameter of 10 to 1000 μm, and in the case of fiber, the filler preferably has an average fiber length of 10 to 1000 μm.
[0045]
The mixing ratio of the PTFE powder and the filler is preferably 2.5 to 100 parts, more preferably 5 to 80 parts, with respect to 100 parts (parts by weight) of PTFE powder. preferable.
[0046]
The organic liquid used in the present invention may be any organic liquid that forms a liquid-liquid interface with water and can exist as droplets in water, and can form a liquid-liquid interface by forming liquid droplets in water. If so, it may be slightly soluble in water. Specific examples include alcohols such as 1-butanol and 1-pentanol; ethers such as diethyl ether and dipropyl ether; ketones such as methyl ethyl ketone and 2-pentanone; aliphatic hydrocarbons such as pentane and dodecane; Aromatic hydrocarbons such as benzene, toluene, xylene; methylene chloride, tetrachloroethylene, trichloroethylene, chloroform, chlorobenzene, trichlorotrifluoroethane, monofluorotrichloromethane, difluorotetrachloroethane, 1,1,1-trichloroethane, 1,1-dichloro -2,2,3,3,3-pentafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-2,2,2-trifluoroethane 1,1-dichloro Or the like can be used halogenated hydrocarbons such as 1-fluoroethane. Of these, halogenated hydrocarbons are preferred, and in particular, 1,1,1-trichloroethane, 1,1-dichloro-2,2,3,3,3-pentafluoropropane, 1,3-dichloro-1,1,2 , 2,3-pentafluoropropane, 1,1-dichloro-2,2,2-trifluoroethane, 1,1-dichloro-1-fluoroethane, and other chlorinated hydrocarbons and fluorochlorinated hydrocarbons are preferred. This is because they are nonflammable and satisfy the requirements of chlorofluorocarbon regulations. These organic liquids may be used alone or in combination of two or more.
[0047]
The addition amount of the organic liquid that forms the liquid-liquid interface with water is 30 to 80% (% by weight, the same applies hereinafter) to the total amount of PTFE powder and filler, and 40 to 60%. Is preferred.
[0048]
In the present invention, as described above, it is considered that granulation of PTFE powder containing a filler proceeds in an organic liquid droplet that forms a liquid-liquid interface with water, but depending on the function of a specific nonionic surfactant. Since the droplets are smaller and have a more spherical shape, it is considered that the average particle size is small, particles having a nearly spherical shape are obtained, and the apparent density of the granular powder is increased.
[0049]
Specific nonionic surfactants are segmented polyalkylene glycols having a hydrophobic segment composed of poly (oxyalkylene) units having 3 to 4 carbon atoms and a hydrophilic segment composed of poly (oxyethylene) units.
[0050]
Examples of segmented polyalkylene glycols having a hydrophobic segment and a hydrophilic segment include those represented by the formula (IV):
[0051]
[Chemical 3]

(Where A is
[0052]
[Formula 4]

p is preferably an integer of 5 to 200, and q is an integer of 2 to 400). Of these, p is preferably 15 to 40 and q is preferably 7 to 100 from the viewpoint of being easily adsorbed to the PTFE resin. As commercially available products, for example, Pronon # 208, Pronon # 104 (both are nonionic surfactants manufactured by NOF Corporation) and the like can be used.
[0053]
The addition amount of the specific nonionic surfactant is 0.01 to 5%, preferably 0.1 to 0.3%, based on the total amount of the PTFE powder and the filler.
[0054]
By using a surfactant within this range, it is possible to obtain a granular powder having a substantially spherical shape, a small particle size, a sharp particle size distribution, excellent powder flowability, a small charge amount, and a large apparent density. available.
[0055]
In addition, when using a normal nonionic surfactant, when using white fillers such as glass, such as glass fiber, titanium oxide, titanate and / or boron nitride, depending on the type of surfactant used, after firing The resulting molded product may be colored. However, if the specific nonionic surfactant is used, it is possible to obtain a molded article having high whiteness (Z value) that is not colored even when a white filler is used.
[0056]
In the production method (3), wet pulverization of the PTFE water-containing powder is performed by a pulverizer of a type that is wet and pulverized by impact force. Various types of pulverizers are known, but in the wet pulverization, it is desirable that only fine powder pulverized to a desired particle size can be taken out simultaneously with pulverization. When selecting from a type of pulverizer in which the impact force is applied by a hammer, it is desirable that the peripheral speed of the hammer be as large as possible.
[0057]
One of the pulverizers satisfying such conditions is, for example, “free pulverizer (JIYU MILL)” manufactured by Nara Machinery Co., Ltd. In this pulverizer, the pulverization chamber has a flat cylinder shape, and a large number of rod-shaped protrusions having a rectangular or oblong cross section are implanted in the two opposing side walls, and the disk-shaped rotation rotates in the center of the pulverization chamber. A rotor is installed in parallel with the two side wall surfaces, and a large number of rod-like protrusions similar to the side walls are implanted on both the front and back surfaces of the rotor so as not to collide with the rod-like protrusions on the side wall when the rotor rotates. Have.
[0058]
The PTFE water-containing powder is supplied to the central portion of the pulverizer and blown away in the outer circumferential direction by the centrifugal force of the rotation of the rotor, collides with the side walls and the rod-shaped protrusions of the rotor, and is pulverized by the impact force. An annular perforated plate is provided on the outer periphery of the crushing chamber in the rotor rotation direction, and only particles pulverized smaller than the hole diameter of the perforated plate pass through the holes and are taken out of the perforated plate. The perforated plate may be a net of metal or the like, and various types such as a thin plate of metal or the like having a large number of holes can be employed. The particle size of the particles obtained varies depending on the pore size. The smaller the pore size, the smaller the particle size of the particles obtained. However, since the particles are wet with water, the particle size of the particles actually taken out is It is considerably smaller than the hole diameter of each hole opened in.
[0059]
One reason why the free pulverizer can finely pulverize the powder even when the powder is in a wet state is considered to be that, for example, a high rotor rotational speed of about 100 m / s is obtained.
[0060]
In addition, as a hammer type pulverizer that can obtain a peripheral speed equal to or higher than that of the free pulverizer, for example, “Coloplex” or “Contraplex” manufactured by Hosokawa Micron Co., Ltd., Nippon Pneumatic ( There is "Fine Mill" manufactured by Co., Ltd. All of these are suitable for pulverization under dry conditions.If they are used in the presence of water, the peripheral speed decreases or the wind classification method is used as the classification mechanism. Ai wind classification does not work, causing the phenomenon that particles larger than the target particle size are classified and discharged. Basically, there are shear mills such as colloid mills and pulverizers as pulverizers by wet pulverization, but these pulverizers cannot be used because the PTFE powder is altered by extreme shearing force.
[0061]
The present invention is also characterized in that agitation and powder crushing are used in combination during granulation.
[0062]
Crushing is a means to reduce the secondary particle size by partially crushing a granule of an appropriate size already generated as a secondary aggregate of primary particles. It can carry out by the method of stirring.
[0063]
Stirring and crushing may be performed in parallel at the same time, or stirring and crushing may be performed separately.
[0064]
By using agitation and pulverization in combination, the apparent density is high, and an excellent effect is obtained that a granulated product that is finely divided is obtained.
[0065]
Here, the disintegration mechanism for powder particles is to partially disintegrate a granule of an appropriate size already generated as a secondary aggregate of primary particles to reduce the secondary particle size. A mechanism that can be used.
[0066]
Next, the apparatus used in the production method of the present invention will be exemplarily described with reference to the drawings. That is, FIG. 1 and FIG. 2 are schematic longitudinal sectional views of the apparatus. In FIG. 1, reference numeral 1 denotes a stirring tank. A rotating shaft 2 is arranged vertically in the center of the stirring tank 1, stirring blades 3 are provided radially at the lower end of the rotating shaft, and the upper end is a motor. 4 is connected. Reference numeral 5 denotes a liquid medium supply port. Reference numeral 6 denotes a crusher, and reference numeral 9 denotes a motor. The crusher 6 is connected to the bottom and top of the agitation tank 1 by transfer pipes 7 and 8, respectively. As the crusher 6, a turbine blade cutter may rotate inside the cylindrical body to transfer the liquid medium while crushing the filler-containing PTFE powder particles contained in the medium. As such an apparatus, for example, a pipeline homomixer (manufactured by Koki Kogyo Co., Ltd.) having a cutter and a stator that applies cutting and impact and a desindelator (manufactured by Komatsu Ltd.) are suitable. . Thus, in order to perform granulation, a liquid medium containing filler-filled PTFE powder is charged into the stirring tank 1 from the liquid medium supply port 5 and stirred by the stirring blade 3, and the stirring tank 1 is stirred simultaneously or after stirring. The liquid medium is withdrawn from the bottom of the tube by the transfer pipe 7 and passed through the crusher 6, whereby the formed and mixed large-diameter particles are crushed and returned to the stirring tank 1 from the transfer pipe 8. Thus, the agglomeration with uniform particle size can be obtained by performing the agitation granulation in the agitation tank 1 and the crushing of the large particle size in the crusher 6 simultaneously, sequentially or alternately. It is done. In this case, the same agglomerated powder can also be obtained by circulating the liquid medium while crushing the particles using only the crusher 6 without moving the stirrer. The reason is considered that the stirring effect is achieved by the circulation of the liquid medium by the crusher.
[0067]
FIG. 2 is a schematic longitudinal sectional view showing an embodiment of another apparatus that can be employed in the production method of the present invention. In the stirring tank 10, a crusher 21 (disper blade) and a stirring blade provided on the rotary shaft 11 are shown. 12 are juxtaposed. Reference numeral 13 denotes a motor for the rotary shaft 11, and 22 denotes a motor for the crusher 21. The stirring blade 12 is attached to the boss 14 at the lower end of the rotating shaft 11 in a radial and spiral manner. Accordingly, in this case, the aqueous medium in the tank is stirred by the stirring blade 12 and the PTFE powder containing filler contained therein is granulated, and the crusher 21 crushes the particles.
[0068]
In the present invention, it is preferable to prepare a slurry of PTFE powder with filler prepared as described above in a stirring tank for granulation and perform stirring granulation and pulverization, but in some cases, PTFE with filler is filled. A method in which a powder previously wetted with a small amount of water is mixed with the remainder of the liquid medium in a stirring tank, or a liquid medium is charged in the stirring tank in advance, and a PTFE powder containing filler is added thereto and stirred. It can also be adopted.
[0069]
The slurry of filler-filled PTFE powder is granulated by the effect of stirring. At the same time or after granulation, large particles, for example, 2000 μm or more are crushed by a pulverizer, and finally coarse particles exceeding 1000 μm are formed. A powder having a uniform particle size with an average particle size of 500 μm or less is contained.
[0070]
Specific examples of the production methods (1) to (3) of the filler-filled PTFE granular powder of the present invention include the following production methods.
[0071]
Manufacturing method (1)
Put 1-5 liters of ion-exchanged water in a granulation tank with an internal volume of 10 liters. To this is added 0.9 to 1.9 kg of PTFE powder, followed by 0.075 to 0.8 kg of filler.
[0072]
Next, 4 to 200 ml of a 5% aqueous solution of a specific nonionic surfactant is added, and the mixture is stirred for 2 to 5 minutes at a stirring speed of 2000 to 3000 rpm with a 100φ disper blade, and then stirred for 5 to 10 minutes. Continue.
[0073]
Further, 450 to 1500 ml of an organic liquid forming a liquid-liquid interface with water is added, and the mixture is granulated by stirring for 1-2 minutes at a stirring speed of 1000 to 2000 rpm with a 100φ disper blade.
[0074]
Next, 0.5 to 5 liters of water is added, and the particles are sized for 0 to 30 minutes with a cone blade at a stirring speed of 600 to 900 rpm at a temperature in the range of 10 to 30 ° C.
[0075]
Next, the temperature in the granulation tank is raised to a temperature in the range of 37.5 to 38.0 ° C. over 15 to 60 minutes, and held at that temperature for 0 to 60 minutes.
[0076]
The temperature holding step and the mixing step using the disper blade immediately after the addition of the organic liquid that forms the water-liquid-liquid interface, the filler is, for example, glass fiber, bronze powder, gold powder, silver powder, copper powder, stainless steel. In the case of powder, stainless steel fiber, nickel powder, nickel fiber, or other metal fiber or metal powder, no separation is performed from the viewpoint of filler separation.
[0077]
Next, the stirring is stopped, the granulated product and water are separated using a 150 mesh sieve, and the granulated product is dried in an electric furnace at 165 ° C. for 16 hours to obtain the PTFE granular material containing the filler of the present invention. Obtain powder.
[0078]
In such a production method (1), for example, granular powder having the following powder physical properties and molded product physical properties can be obtained. This is a method for producing a filler-filled PTFE granular powder that cannot be obtained by a conventional production method, for example, such that a complicated process such as taking out the powder or pre-mixing the PTFE powder and the filler is unnecessary.
[0079]
(Physical properties of PTFE granular powder with filler)
Apparent density: 0.70 g / cm^Threethat's all
0.70 g / cm^ThreeIf it is smaller, the mold filling amount becomes smaller.
[0080]
Fluidity: 6 times or more
Less than 5.5 times is inferior in hopper fluidity. 8 times is particularly preferable.
[0081]
Angle of repose: 40 degrees or less
A powder exceeding 40 degrees is not preferable because of poor fluidity.
[0082]
However, the apparent density is 0.9 g / cm^Three1.0 g / cm^ThreeIf it is less than 38 degrees, the apparent density is 1.0 g / cm.^ThreeIn the above case, it is 36 degrees or less.
[0083]
Usually, the repose angle of powder becomes smaller as the apparent density is higher due to the influence of gravity. Therefore, the angle of repose of the powder obtained by the method of the present invention also varies depending on the apparent density, but is smaller than the powder obtained by the prior art.
[0084]
The angle of repose of the powder obtained by the prior art has an apparent density of 0.7 g / cm.^Three0.9 g / cm^ThreeIf it is less than 40 degrees, the apparent density is 0.9 g / cm.^Three1.0 g / cm^ThreeIf it is less than 38 degrees, the apparent density is 1.0 g / cm.^ThreeIn the above case, it exceeds 36 degrees.
[0085]

When the granulated powder after granulation has a particle size distribution within this range, the particle size is uniform, which is preferable because there is no uneven filling in the mold. In particular, it is preferable that the granular powder existing on the 10 mesh and 20 mesh sieves is 0%.
[0086]
Particle size distribution B: 50% by weight or more
When the granulated granular powder has this particle size distribution, there is no uneven filling of the mold, which is preferable. In particular, it is preferably 60% by weight or more.
[0087]
Average particle size: 500 μm or less
When it exceeds 500 μm, it becomes impossible to fill a thin mold. Particularly preferably, the thickness is 150 to 400 μm from the viewpoint of filling into a thin mold.
[0088]
Charge amount: 50V or less
The PTFE powder charged to exceed 50V adheres not only to the mold for molding but also to the hopper, feeder, etc. due to static electricity, and consequently inhibits fluidity. Preferably, it is 10 V or less, and the fluidity does not decrease at all with the charge amount.
[0089]
(Physical properties of molded products)
Tensile strength: 100kgf / cm²that's all
100kgf / cm²Smaller moldings have poor mechanical strength. Preferably, 150 kgf / cm²That's all, depending on the application.
[0090]
Elongation: 100-400%
Molded articles smaller than 100% may be cut during mounting or processing on equipment. Preferably it is 150% or more.
[0091]
Surface roughness: 3.0 μm or less
A molded product exceeding 3.0 μm has a large surface irregularity, which is not preferable. Particularly preferably, it is 2.0 μm or less.
[0092]
Whiteness (Z value): 80 or more (in the case of glass fiber) Originally, a high whiteness is preferred for the PTFE molded product, and a high whiteness is preferable from the viewpoint of commercial value.
[0093]
Manufacturing method (2)
Put 1-5 liters of ion-exchanged water in a granulation tank with an internal volume of 10 liters. To this, 0.9 to 1.9 kg of PTFE powder is added.
[0094]
Next, 4 to 200 ml of a 5% aqueous solution of a specific nonionic surfactant is added, and the mixture is stirred for 2 to 5 minutes at a stirring speed of 2000 to 3000 rpm with a 100φ disperse blade to be in a slurry state.
[0095]
Next, 0.075 to 0.8 kg of filler is added, and the mixture is stirred for 2 to 15 minutes with a stirring speed of 2000 to 4000 rpm with a 100φ disper blade.
[0096]
Further, an organic liquid that forms a liquid-liquid interface with water is added. After this operation, the steps up to obtaining the filler-filled PTFE granular powder of the present invention are the same as the production method (1).
[0097]
In the production method (2), for example, granular powder having the following powder physical properties and molded product physical properties can be obtained. This is a method for producing a filler-filled PTFE granular powder that cannot be obtained by a conventional production method, such as the need for a complicated process such as taking out or mixing PTFE powder and a filler in advance.
[0098]
(Physical properties of PTFE granular powder with filler)
Apparent density: 0.70 g / cm^Threethat's all
0.70 g / cm^ThreeIf it is smaller, the mold filling amount becomes smaller.
[0099]
Fluidity: 6 times or more
Less than 5.5 times is inferior in hopper fluidity. 8 times is particularly preferable.
[0100]
Angle of repose: 40 degrees or less
A powder exceeding 40 degrees is not preferable because of poor fluidity.
[0101]
However, the apparent density is 0.9 g / cm^Three1.0 g / cm^ThreeIf it is less than 38 degrees, it is 38 degrees or less, and if the apparent density is 1.0 or more, it is 36 degrees or less.
[0102]

When the granulated powder after granulation has a particle size distribution within this range, the particle size is uniform, which is preferable because there is no uneven filling in the mold. In particular, it is preferable that the granular powder existing on the 10 mesh and 20 mesh sieves is 0%.
[0103]
Particle size distribution B: 50% by weight or more
When the granulated granular powder has this particle size distribution, there is no uneven filling of the mold, which is preferable. In particular, it is preferably 60% by weight or more.
[0104]
Average particle size: 500 μm or less
When it exceeds 500 μm, it becomes impossible to fill a thin mold. Particularly preferably, the thickness is 150 to 400 μm from the viewpoint of filling into a thin mold.
[0105]
Charge amount: 50V or less
The PTFE powder charged to exceed 50V adheres not only to the mold for molding but also to the hopper, feeder, etc. due to static electricity, and consequently inhibits fluidity. Preferably, it is 10 V or less, and the fluidity does not decrease at all with the charge amount.
[0106]
(Physical properties of molded products)
Tensile strength: 100kgf / cm²that's all
100kgf / cm²Smaller moldings have poor mechanical strength. Preferably, 150 kgf / cm²That's all, depending on the application.
[0107]
Elongation: 100-400%
Molded articles smaller than 100% may be cut during mounting or processing on equipment. Preferably it is 150% or more.
[0108]
Surface roughness: 3.0 μm or less
A molded product exceeding 3.0 μm has a large surface irregularity, which is not preferable. Particularly preferably, it is 2.0 μm or less.
[0109]
Whiteness (Z value): 80 or more (in the case of glass fiber) Originally, a high whiteness is preferred for the PTFE molded product, and a high whiteness is preferable from the viewpoint of commercial value.
[0110]
Manufacturing method (3)
PTFE coarse particles having an average particle diameter of 2 to 3 mm taken out from the polymerization system in a usual suspension polymerization method are coarsely pulverized using a pipeline homomixer, and an average particle diameter of 200 to 1000 μm and a water content of 5 to 30% by weight are obtained. A PTFE water-containing powder is obtained.
[0111]
Next, the PTFE water-containing powder was put into the free pulverizer, and a screen provided with a large number of holes having a hole diameter of 0.1 to 0.3 mm was used as a perforated plate for classification. The power was 2.2 kW and the throughput was 1.0. From the step of performing wet pulverization under a condition of ˜100 kg / hr to obtain a powder having an average particle size of 20 to 100 μm and a moisture content of 5 to 30%, and adding 1.575 to 2.6 kg of this powder to ion-exchanged water, The process until the filler-containing PTFE granular powder of the invention is obtained is the same as the production method (2).
[0112]
In this production method (3), for example, the following granular powder having powder properties and molded product properties can be obtained. This is a method for producing a filler-filled PTFE granular powder that cannot be obtained by a conventional production method, for example, such that a complicated process such as taking out the powder or pre-mixing the PTFE powder and the filler is unnecessary.
[0113]
(Physical properties of PTFE granular powder with filler)
Apparent density: 0.70 g / cm^Threethat's all
0.70 g / cm^ThreeIf it is smaller, the mold filling amount becomes smaller.
[0114]
Fluidity: 6 times or more
Less than 5.5 times is inferior in hopper fluidity. 8 times is particularly preferable.
[0115]
Angle of repose: 40 degrees or less
A powder exceeding 40 degrees is not preferable because of poor fluidity.
[0116]
However, the apparent density is 0.9 g / cm^Three1.0 g / cm^ThreeIf it is less than 38 degrees, it is 38 degrees or less, and if the apparent density is 1.0 or more, it is 36 degrees or less.
[0117]

When the granulated powder after granulation has a particle size distribution within this range, the particle size is uniform, which is preferable because there is no uneven filling in the mold. In particular, it is preferable that the granular powder existing on the 10 mesh and 20 mesh sieves is 0%.
[0118]
Particle size distribution B: 50% by weight or more
When the granulated granular powder has this particle size distribution, there is no uneven filling of the mold, which is preferable. In particular, it is preferably 60% by weight or more.
[0119]
Average particle size: 500 μm or less
When it exceeds 500 μm, it becomes impossible to fill a thin mold. Particularly preferably, the thickness is 150 to 400 μm from the viewpoint of filling into a thin mold.
[0120]
(Physical properties of molded products)
Tensile strength: 100kgf / cm²that's all
100kgf / cm²Smaller moldings have poor mechanical strength. Preferably, 150 kgf / cm²That's all, depending on the application.
[0121]
Elongation: 100-400%
Molded articles smaller than 100% may be cut during mounting or processing on equipment. Preferably it is 150% or more.
[0122]
Surface roughness: 3.0 μm or less
A molded product exceeding 3.0 μm has a large surface irregularity, which is not preferable. Particularly preferably, it is 2.0 μm or less.
[0123]
Whiteness (Z value): 80 or more (in the case of glass fiber) Originally, a high whiteness is preferred for the PTFE molded product, and a high whiteness is preferable from the viewpoint of commercial value.
[0124]
As conditions in the manufacturing method of the filler-containing PTFE granular powder of the present invention, the following are preferable.
[0125]

[0126]
More preferably

[0127]

[0128]
More preferably

[0129]

[0130]
More preferably

[0131]
【Example】
Next, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.
[0132]
Example 1 [Production method (1)]
PTFE powder (Daikin Kogyo Co., Ltd., Polyflon M-12, PTFE homopolymer) 1.275 kg with 1.5 liters of ion-exchanged water in a granulation tank having an internal volume of 10 liters and an average particle size after pulverization of 31 μm (Dry basis) and 0.225 kg of glass fiber (EPG40M-10A manufactured by Nippon Electric Glass Co., Ltd., average diameter: 12 μm, average fiber length: 80 μm) previously treated with an aminosilane coupling agent are sequentially added.
[0133]
Next, a 5% by weight aqueous solution of an ethylene oxide block polymer of polypropylene glycol (molecular weight of polyoxypropylene segment 1000, polyoxyethylene segment molecular weight 667. Pronon # 104 manufactured by NOF Corporation) as a specific nonionic surfactant. Add 90 ml.
[0134]
Next, when stirring for 2 minutes at a stirring speed of 3000 rpm using a 100φ disperse blade, the PTFE powder and the filler become wet and become a viscous slurry with a viscosity of 10 to 1000 cps. In this state, the mixture is further stirred for 3 minutes. And mix.
[0135]
Next, 750 ml of an organic liquid (methylene chloride) that forms a liquid-liquid interface with water is added, and granulated by stirring for 1-2 minutes at a stirring speed of 1500 to 2000 rpm using a 100φ disper blade.
[0136]
Next, 4.5 liters of water is added, and the mixture is sized for 15 minutes at 25 ° C. ± 2 ° C. with stirring at 800 rpm using a cone blade.
[0137]
Next, the temperature in the tank is raised to 38 ° C. over 20 minutes to stop stirring, and the granulated product and water are separated using a 150-mesh sieve, and the obtained granulated product is placed in an electric furnace. And dried at 165 ° C. for 16 hours to obtain the filler-filled PTFE granular powder of the present invention, and the following test was performed.
[0138]
Apparent density: Measured according to JIS K 6891-5.3.
[0139]
Average particle size after pulverization (particle size of primary particles)
Wet sheave method: JIS standard sieve 20 mesh (sieving opening 840 μm), 250 mesh (sieving opening 62 μm), 270 mesh (sieving opening 53 μm), 325 mesh (sieving opening 44 μm) and 400 mesh (sieve opening) Aperture 37 μm) is used. First, a 20 mesh screen is overlaid on a 250 mesh screen. Place a 5g powder sample on a 20 mesh sieve and use a shower sprayer to obtain about 3 liters / m²Carefully wash off the lower screen by spraying carbon tetrachloride at a rate of about 30 seconds. When the sample is completely washed out, remove the upper sieve and spray the lower sieve with mist for about 4 minutes. Thereafter, the lower sieve is air dried and the weight of the dry powder retained on the sieve is measured. This series of operations is repeated for each new 5 g powder sample using a 20 mesh screen and one of the other three small mesh screens. Multiply the weight of the powder retained on each sieve by 20 to obtain the cumulative weight percentage value, and then plot these numbers against the opening of the sieve on a logarithmic probability paper. These points are connected by a straight line, and the cumulative percentage is 50 (d₅₀) And 84 (d₃₄) And the wet sheave size (d_WS) Is calculated.
[0140]
[Expression 1]

Fluidity: Measured according to the method described in JP-A-3-259925.
[0141]
That is, as the measuring device, as shown in FIG. 3 (corresponding to FIG. 3 described in JP-A-3-259925), upper and lower hoppers 31 and 32 supported by a support base 42 with their center lines aligned are used. The upper hopper 31 has a diameter of 74 mm at the inlet 33, a diameter of 12 mm at the outlet 34, and a height of 123 mm from the inlet 33 to the outlet 34, and has a partition plate 35 at the outlet 34, thereby holding or dropping the powder therein. Can be done as appropriate. The lower hopper 32 has a diameter of 76 mm at the inlet 36, a diameter of 12 mm at the outlet 37, and a height of 120 mm from the inlet 36 to the outlet 37, and a partition plate 38 is provided at the outlet 37 like the upper hopper. The distance between the upper hopper and the lower hopper is adjusted so that the distance between the partition plates is 15 cm. In FIG. 3, 39 and 40 are outlet covers for the respective hoppers, and 41 is a receiver for the dropped powder.
[0142]
The fluidity is measured by leaving about 200 g of the powder to be measured in a room adjusted to 23.5 to 24.5 ° C. for 4 hours or more and sieving with 10 mesh (opening of 1680 microns) and then at the same temperature. .
[0143]
(I) First, just one cup of the powder to be measured is put into the upper hopper 31 in a cup with a capacity of 30 cc, and the partition plate 35 is immediately pulled out to drop the powder into the lower hopper. If it doesn't fall, pick it up with a wire. After the powder has completely dropped into the lower hopper 32, leave it for 15 ± 2 seconds, then pull out the partition plate 38 of the lower hopper and observe whether the powder flows down from the outlet 37. Is determined to have fallen.
[0144]
(II) Check if the same measurement as above is repeated 3 times, and if it falls 2 times or more out of 3 times, the fluidity is judged as “good”. It is determined as “bad”. If only one of the three drops, the same measurement is performed twice. If both drops, the fluidity of the powder is determined to be “good”. Otherwise, The fluidity is judged as “poor”.
[0145]
(III) For the powder determined to have good fluidity in the above measurement, put the next two cups of the same 30 cc cup into the upper hopper and perform the same measurement as described above. When the fluidity is “good”, the number of cups of the powder is increased in sequence, and until it becomes “bad”, measure up to 8 cups. In each measurement, the powder flowing out from the lower hopper in the previous measurement may be reused.
[0146]
(IV) According to the above measurement, the PTFE powder becomes more difficult to flow down as the amount used increases.
[0147]
Therefore, the “fluidity” of the powder is determined by subtracting 1 from the number of cups when the fluidity becomes “poor”.
[0148]
Particle size distribution A and average particle size of granulated powder: Overlay standard sieves of 10, 20, 32, 48 and 60 mesh (inch mesh) in order from the top, put PTFE granular powder on 10 mesh sieve, vibrate the sieve and drop the fine PTFE granular powder particles sequentially downward After calculating the percentage of PTFE granular powder remaining on each sieve in%, the cumulative percentage (vertical axis) of the residual ratio is graduated on the logarithmic probability paper with respect to the opening of each sieve (horizontal axis). These points are connected by a straight line, and the particle size at which the ratio is 50% on this straight line is obtained, and this value is taken as the average particle size.
[0149]
Particle size distribution B: Weight ratio of particles having a diameter of 0.7 to 1.3 times the average particle diameter to all particles, calculated by multiplying the average particle diameter by 0.7 or 1.3 times, and cumulative The weight percentage is determined by writing that point in the curve.
[0150]
Tensile strength (hereinafter also referred to as TS) and elongation (hereinafter also referred to as EL): 25 g of powder is filled in a mold with an inner diameter of 100 mm, and the final pressure is about 500 kg / cm over about 30 seconds.²The pressure is gradually applied until it becomes, and the pressure is maintained for another 2 minutes to prepare a preform. The preform is taken out from the mold, placed in an electric furnace maintained at 365 ° C., fired for 3 hours, and taken out to obtain a fired body. A test piece is punched out of this fired body with JIS dumbbell No. 3, and is pulled at a tensile rate of 200 mm / min using an autograph with a total load of 500 kg according to JIS K6891-58, and the stress and elongation at break are measured.
[0151]
Angle of repose: Measured using a powder tester manufactured by Hosokawa Micron.
[0152]
Charge amount: Ion systems, Inc. Measurement is performed using a handy electrostatic measuring instrument SFM775.
[0153]
Whiteness (Z value): 200 g of granulated powder is filled in a 50 mm diameter mold, and molding pressure is 500 kg / cm.²For 5 minutes, and the resulting preform (about 50 mm in diameter and about 50 mm in height) was heated from room temperature to 365 ° C. at a rate of 50 ° C./hr and held at 365 ° C. for 5.5 hours. After that, the molded product cooled at 50 ° C./hr was divided by a lathe about 25 mm (center portion) from the end, and the Z value of the center portion of the cut-out portion was determined according to the XYZ series Z defined by the International Lighting Commission. It was measured based on the value measurement method.
[0154]
Surface roughness: Filling a mold with a diameter of 50 mm with a powder of 210 g, a molding pressure of 500 kg / cm²The obtained preform is heated from room temperature to 365 ° C. at a heating rate of 50 ° C./hr, held at 365 ° C. for 5.5 hours, and then cooled at 50 ° C./hr. The upper surface of the obtained molded product was subjected to the center line average roughness (Ra) method described in JIS B 0601 using a surface roughness measuring instrument manufactured by Tokyo Seimitsu Co., Ltd.
Measured.
[0155]
In addition, about the PTFE granular powder with a filler obtained in Example 1, the photograph of the particle | grains in this powder was performed with the following method.
[0156]
Particle shape: Photographing was performed on an image with a magnification of 100 times or 200 times using an optical microscope video microscope manufactured by Sony Corporation.
[0157]
The results are shown in Table 1 and FIG. 4 (100 times) and FIG. 5 (200 times).
[0158]
Examples 2-3
A filler-containing PTFE powder was produced in the same manner as in Example 1 except that the amount of the specific nonionic surfactant used in Example 1 was changed to the amount shown in Table 1, and various physical properties were examined in the same manner as in Example 1. It was. The results are shown in Table 1.
[0159]
Example 4 [Production method (2)]
PTFE powder (Polyflon M-12, manufactured by Daikin Industries, Ltd., PTFE homopolymer) 1.275 kg with 1.5 liters of ion-exchanged water in a granulation tank having an internal volume of 10 liters and an average particle size after grinding of 31 μm Add (dry basis).
[0160]
Next, 90 ml of a 5% aqueous solution of an ethylene oxide block polymer of polypropylene glycol (Pronon # 104) is added as a specific nonionic surfactant.
[0161]
Next, when stirring is performed for 2 minutes at a rotational speed of 3000 rpm using a 100φ disper blade, the PTFE powder gets wet with water and becomes a viscous slurry with a viscosity of 10 to 1000 cps.
[0162]
Further, when 0.225 kg of glass fiber (same as in Example 1) that has been subjected to water repellency treatment in advance with an aminosilane coupling agent is added and stirred for 2 minutes at a rotational speed of 3000 rpm using a 100φ disper blade, the glass fiber is also water. To become a viscous slurry with a viscosity of 10 to 1000 cps. In this state, the mixture is further stirred for 3 minutes and mixed.
[0163]
Next, 750 ml of an organic liquid (methylene chloride) that forms a liquid-liquid interface with water is added, and granulated by stirring for 1-2 minutes at a stirring speed of 1500 to 2000 rpm using a 100φ disper blade.
[0164]
Next, 4.5 liters of water is added, and the mixture is sized for 15 minutes at 25 ° C. ± 2 ° C. with stirring at 800 rpm using a cone blade.
[0165]
Next, the temperature in the tank is raised to 38 ° C. over 20 minutes to stop stirring, and the granulated product and water are separated using a 150-mesh sieve, and the obtained granulated product is placed in an electric furnace. , Dried at 165 ° C. for 16 hours to obtain a PTFE granular powder containing the filler of the present invention, and the same test as in Example 1 was performed. The results are shown in Table 1.
[0166]
The obtained PTFE powder containing filler was observed with a microscope and photographed in the same manner as in Example 1. The photograph taken (200 times) is shown in FIG.
[0167]
Example 5 [Production method (3)]
Put 1600 liters of deoxygenated pure water in a stainless steel autoclave with a stirrer with a capacity of 2000 liters, replace the air inside with nitrogen, and then replace with tetrafluoroethylene. While maintaining the pressure, tetrafluoroethylene was injected until the internal pressure reached 6 atm._Four)₂S₂O₂And FeSO_FourIs added and the tetrafluoroethylene is polymerized while stirring. Since the pressure decreases with the polymerization, tetrafluoroethylene is continuously added so that the internal pressure is maintained at 6 atm. Stirring was stopped after 4 hours, and the content was taken out after recovering tetrafluoroethylene. PTFE coarse particles having an average particle diameter of 2 to 3 mm, which is a polymer produced, are produced by T.W. K. A coarse PTFE powder having an average particle size of about 400 μm is obtained by coarse pulverization using a pipeline homomixer 2S type machine (manufactured by Tokushu Kika Kogyo Co., Ltd.).
[0168]
This PTFE crude powder was put into a free pulverizer M-2 type (manufactured by Nara Machinery Co., Ltd.) without drying and containing about 25% by weight of water, and wet pulverized. At this time, a screen provided with a large number of holes having a hole diameter of 0.25 mm was used as a porous plate for classification, and wet pulverized with a power of 2.2 KW and a throughput of 38 kg / hr to obtain PTFE powder having an average particle size of 36 μm.
[0169]
Into a granulation tank having an internal volume of 10 liters, 1.5 liters of ion-exchanged water is added, and 1.275 kg (dry basis) of the PTFE powder having an average particle size of 36 μm and wet-pulverized is added.
[0170]
Next, 90 ml of a 5% aqueous solution of an ethylene oxide block polymer of polypropylene glycol (Pronon # 104) is added as a specific nonionic surfactant.
[0171]
Next, when stirring is performed for 2 minutes at a rotational speed of 3000 rpm using a 100φ disper blade, the PTFE powder gets wet with water and becomes a viscous slurry with a viscosity of 10 to 1000 cps.
[0172]
Further, when 0.225 kg of glass fiber (same as in Example 1) that has been subjected to water repellency treatment in advance with an aminosilane coupling agent is added and stirred for 2 minutes at a rotational speed of 3000 rpm using a 100φ disper blade, the glass fiber is also water. To become a viscous slurry with a viscosity of 10 to 1000 cps. In this state, the mixture is further stirred for 3 minutes and mixed.
[0173]
Next, 750 ml of an organic liquid (methylene chloride) that forms a liquid-liquid interface with water is added, and granulated by stirring for 1-2 minutes at a stirring speed of 1500 to 2000 rpm using a 100φ disper blade.
[0174]
Next, 4.5 liters of water is added, and the mixture is sized for 15 minutes at 25 ° C. ± 2 ° C. with stirring at 800 rpm using a cone blade.
[0175]
Next, the temperature in the tank is raised to 38 ° C. over 20 minutes to stop stirring, and the granulated product and water are separated using a 150-mesh sieve, and the obtained granulated product is placed in an electric furnace. , Dried at 165 ° C. for 16 hours to obtain a PTFE granular powder containing the filler of the present invention, and the same test as in Example 1 was performed. The results are shown in Table 1.
[0176]
The obtained PTFE powder containing filler was observed with a microscope and photographed in the same manner as in Example 1. The photograph (200 times) taken is shown in FIG.
[0177]
[Table 1]

In the particle size distribution A column of Table 1, 10on is on a 10 mesh screen, 20on is on a 20 mesh screen, 32on is on a 32 mesh screen, 48on is on a 48 mesh screen, 60on is 60 mesh. No. 83on indicates the ratio of particles remaining on the 83 mesh sieve, and 83pass indicates the ratio of particles passing through the 83 mesh sieve.
[0178]
As is apparent from the results in Table 1, the filler-filled PTFE granular powder obtained by any of the production methods of the present invention has a large apparent density, particularly a small particle size, a sharp particle size distribution, and a small charge amount. Although it has a small particle size, it has excellent fluidity, and a molded product obtained from the granular powder is excellent in tensile strength and elongation, and has a small surface roughness.
[0179]
Moreover, it turns out that the manufacturing method of this invention can control the average particle diameter and particle size distribution of a PTFE granular powder with a filler by the addition amount of a specific surfactant.
[0180]
Moreover, when using a white or transparent filler, the whiteness (Z value) of the obtained molded product is 80 or more, and further 95 or more, which is higher than ever.
[0181]
4 to 5 are Example 1 and FIGS. 6 and 7 are optical micrographs showing the particle structure of the particles in the filler-filled PTFE granular powder of the present invention obtained in Examples 4 and 5, respectively. As is clear from the figure (photograph), it can be seen that the particles in the filler-filled PTFE granular powder of the present invention are substantially spherical.
[0182]
The reason why the filler-filled PTFE granular powder of the present invention is remarkably excellent in powder flowability despite its small average particle diameter is, for example, that the shape of the particles is almost spherical. It is done.
[0183]
【The invention's effect】
The filler-filled PTFE granular powder of the present invention has a large apparent density, and most of the particles are almost spherical, have a small average particle size, a sharp particle size distribution, a small charge amount, and a small average particle size. A molded product having excellent powder flowability and obtained from granular powder has excellent tensile strength and elongation, low surface roughness and high whiteness.
[0184]
In addition, the production methods (1) to (3) of the present invention can provide a filler-filled PTFE granular powder having excellent physical properties as described above, and in particular, the average particle size and particle size depending on the amount of a specific nonionic surfactant. This is a production method that can control the distribution and obtain a granular powder with a sharp particle size distribution.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a granulating apparatus that can be used in the production method of the present invention.
FIG. 2 is a schematic cross-sectional view of another granulation apparatus that can be used in the production method of the present invention.
FIG. 3 is a schematic explanatory diagram of an apparatus used for examining the fluidity of granular powder in the present invention.
4 is an optical micrograph (magnification: 100 times) showing the particle structure of particles in the filler-filled PTFE granular powder of the present invention obtained in Example 1. FIG.
5 is an optical micrograph (magnification: 200 times) showing the particle structure of particles in the filler-filled PTFE granular powder of the present invention obtained in Example 1. FIG.
6 is an optical micrograph (magnification: 200 times) showing the particle structure of particles in the filler-filled PTFE granular powder of the present invention obtained in Example 4. FIG.
7 is an optical micrograph (magnification: 200 times) showing the particle structure of particles in the filler-filled PTFE granular powder obtained in Example 5. FIG.
[Explanation of symbols]
1 Mixing tank
3 Stirring blade
6 Crusher
10 Mixing tank
12 Stirring blade
21 Crusher

Claims (19)

When granulating the polytetrafluoroethylene powder and filler obtained by suspension polymerization in water, the powder and filler are separately poured into water without being mixed in advance. After stirring and mixing in the presence of a nonionic surfactant having a hydrophobic segment comprising a poly (oxyalkylene) unit and a hydrophilic segment comprising a poly (oxyethylene) unit, the mixture is further mixed with water and liquid. A method for producing a filler-filled polytetrafluoroethylene granular powder, which is granulated by stirring in the presence of an organic liquid forming a liquid interface. Hydrophobic composed of poly (oxyalkylene) units having 3 to 4 carbon atoms when granulated by stirring polytetrafluoroethylene powder and filler obtained by suspension polymerization in water. Stirring in the presence of a nonionic surfactant having a segment and a hydrophilic segment composed of poly (oxyethylene) units to form a slurry, adding a filler to the slurry, mixing, and then adding water to a liquid-liquid interface A method for producing a filler-filled polytetrafluoroethylene granular powder, which is granulated by stirring in the presence of an organic liquid that forms an aqueous solution. When the polytetrafluoroethylene powder obtained by suspension polymerization and the filler are granulated by stirring in water, the polytetrafluoroethylene hydrous powder after polymerization is wet-ground without passing through the drying process and put into water. And stirring in the presence of a nonionic surfactant having a hydrophobic segment composed of a poly (oxyalkylene) unit having 3 to 4 carbon atoms and a hydrophilic segment composed of a poly (oxyethylene) unit, A method for producing a filler-filled polytetrafluoroethylene granular powder, comprising adding a filler to a slurry and mixing the mixture, and further stirring and granulating in the presence of an organic liquid that forms a liquid-liquid interface with water. 4. The method according to any one of claims 1 to 3, wherein in the stirring granulation, in addition to the means for stirring, a means for pulverizing the granular powder obtained by granulation is used, and the granulation is performed by combining stirring and pulverization. A process for producing a filler-filled polytetrafluoroethylene granular powder. The method for producing a filler-filled polytetrafluoroethylene granular powder according to any one of claims 1 to 4, wherein the amount of the surfactant is 0.01 to 5% by weight based on the total amount of the polytetrafluoroethylene powder and the filler. . The polytetrafluoroethylene is a tetrafluoroethylene homopolymer or a modified polytetrafluoroethylene obtained by copolymerizing 99 to 99.999 mol% of tetrafluoroethylene and 1 to 0.001 mol% of perfluorovinyl ether. The manufacturing method of the filler-containing polytetrafluoroethylene granular powder in any one of claim | item 1 -5. A filler-containing polytetrafluoroethylene granular powder obtained by the production method according to claim 1, wherein the apparent density of the granular powder is 0.7 g / cm ³ or more. Polytetrafluoroethylene granular powder. The filler-containing polytetrafluoroethylene granular powder according to claim 7, wherein the granular powder has a fluidity of 6 times or more and a charge amount of 50 V or less. The filler-containing polytetrafluoroethylene granular powder according to claim 7, wherein the angle of repose of the granular powder is 40 degrees or less. The filler-containing polytetrafluoroethylene granular powder according to claim 7, wherein the average particle diameter of the granular powder is 500 µm or less. Filled polytetrafluoroethylene particles having an apparent density of 0.7 g / cm ³ or more and less than 0.9 g / cm ³ , an angle of repose of 40 degrees or less, a charge amount of 50 V or less, and an average particle diameter of 500 μm or less. Powder. Filled polytetrafluoroethylene granules having an apparent density of 0.9 g / cm ³ or more and less than 1.0 g / cm ³ , an angle of repose of 38 degrees or less, a charge amount of 50 V or less, and an average particle size of 500 μm or less. Powder. A filler-filled polytetrafluoroethylene granular powder having an apparent density of 1.0 g / cm ³ or more, an angle of repose of 36 degrees or less, a charge amount of 50 V or less, and an average particle diameter of 500 μm or less. The filler-containing polytetrafluoroethylene granular powder according to claim 11, comprising 2.5 to 50% by weight of filler. The filler-containing polytetrafluoroethylene granular powder according to claim 11, which gives a molded product having a surface roughness of 3.0 μm or less. The particle size distribution of the granular powder is 0% of the granular powder remaining on the 10 mesh sieve and 5% or less of the granular powder remaining on the 20 mesh sieve. Polytetrafluoroethylene granular powder. The ratio of particles having a particle size of 0.7 to 1.3 times the average particle size of the particles in the granular powder to the total particles is 50% by weight or more. Polytetrafluoroethylene granular powder. The filler-containing polytetrafluoroethylene granular powder according to any one of claims 7 to 17, wherein the filler is a white or transparent filler. The filler-containing polytetrafluoroethylene granular powder according to claim 18, which gives a molded article having a whiteness (Z value) of 80 or more.

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